diff --git a/Makefile b/Makefile
index 46ad8404..d8cf17ec 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 SRCS = $(wildcard src/*.c)
 HDRS = $(wildcard src/*.h)
-DEFS ?= -DMG_MAX_HTTP_HEADERS=5 -DMG_ENABLE_LINES -DMG_ENABLE_HTTP_DEBUG_ENDPOINT=1 -DMG_ENABLE_DIRECTORY_LISTING=1
+DEFS ?= -DMG_MAX_HTTP_HEADERS=5 -DMG_ENABLE_LINES -DMG_ENABLE_HTTP_DEBUG_ENDPOINT=1 -DMG_ENABLE_DIRECTORY_LISTING=1 -DMG_ENABLE_SSI=1
 CFLAGS ?= -W -Wall -Werror -Isrc -I. -O0 -g $(DEFS) $(TFLAGS) $(EXTRA)
 SSL ?= MBEDTLS
 CDIR ?= $(realpath $(CURDIR))
@@ -99,7 +99,7 @@ mongoose.c: $(SRCS) Makefile
 	(cat src/license.h; echo; echo '#include "mongoose.h"' ; (for F in src/private.h src/*.c ; do echo; echo '#ifdef MG_ENABLE_LINES'; echo "#line 1 \"$$F\""; echo '#endif'; cat $$F | sed -e 's,#include ".*,,'; done))> $@
 
 mongoose.h: $(HDRS) Makefile
-	(cat src/license.h src/version.h ; cat src/arch.h src/arch_*.h src/config.h src/str.h src/log.h src/timer.h src/util.h src/url.h src/iobuf.h src/base64.h src/md5.h src/sha1.h src/event.h src/net.h src/http.h src/tls.h src/ws.h src/sntp.h src/mqtt.h src/dns.h | sed -e 's,#include ".*,,' -e 's,^#pragma once,,')> $@
+	(cat src/license.h src/version.h ; cat src/arch.h src/arch_*.h src/config.h src/str.h src/log.h src/timer.h src/util.h src/url.h src/iobuf.h src/base64.h src/md5.h src/sha1.h src/event.h src/net.h src/http.h src/ssi.h src/tls.h src/ws.h src/sntp.h src/mqtt.h src/dns.h | sed -e 's,#include ".*,,' -e 's,^#pragma once,,')> $@
 
 clean: EXAMPLE_TARGET = clean
 clean: ex
diff --git a/docs/README.md b/docs/README.md
index 0ec21058..e9b66025 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -223,6 +223,7 @@ Here is a list of build constants and their default values:
 |`MG_ENABLE_DIRECTORY_LISTING` | 0 | Enable directory listing for HTTP server |
 |`MG_ENABLE_HTTP_DEBUG_ENDPOINT` | 0 | Enable `/debug/info` debug URI |
 |`MG_ENABLE_SOCKETPAIR` | 0 | Enable `mg_socketpair()` for multi-threading |
+|`MG_ENABLE_SSI` | 0 | Enable serving SSI files by `mg_http_serve_dir()` |
 |`MG_IO_SIZE` | 512 | Granularity of the send/recv IO buffer growth |
 |`MG_MAX_RECV_BUF_SIZE` | (3 * 1024 * 1024) | Maximum recv buffer size |
 |`MG_MAX_HTTP_HEADERS` | 40 | Maximum number of HTTP headers |
@@ -242,7 +243,8 @@ static const char *s_web_root_dir = ".";
 static const char *s_listening_address = "http://localhost:8000";
 
 static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
-  if (ev == MG_EV_HTTP_MSG) mg_http_serve_dir(c, ev_data, s_web_root_dir);
+  struct mg_http_serve_opts opts = {.root_dir = s_web_root_dir};
+  if (ev == MG_EV_HTTP_MSG) mg_http_serve_dir(c, ev_data, &opts);
 }
 
 int main(int argc, char *argv[]) {
@@ -628,11 +630,16 @@ Write a chunk of data in chunked encoding format.
 ### mg\_serve\_dir()
 
 ```c
+struct mg_http_serve_opts {
+  const char *root_dir;     // Web root directory, must be non-NULL
+  const char *ssi_pattern;  // SSI filename pattern, e.g. #.shtml
+};
 void mg_http_serve_dir(struct mg_connection *, struct mg_http_message *hm,
-                       const char *path);
+                       const struct mg_http_serve_opts *opts);
 ```
 
-Serve static files using `path` as a root directory.
+Serve static files according to the given options. Note that in order to
+enable SSI, set a `-DMG_ENABLE_SSI=1` build flag.
 
 
 ### mg\_serve\_file()
diff --git a/examples/complete/main.c b/examples/complete/main.c
index 93980b48..8ccfbb22 100644
--- a/examples/complete/main.c
+++ b/examples/complete/main.c
@@ -129,7 +129,8 @@ static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
                            u->token);
       mg_http_printf_chunk(c, "");
     } else {
-      mg_http_serve_dir(c, ev_data, "web_root");
+      struct mg_http_serve_opts opts = {.root_dir = "web_root"};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
 }
@@ -146,7 +147,7 @@ static void broadcast_mjpeg_frame(struct mg_mgr *mgr) {
   char *data = mg_file_read(path);  // Read next file
   struct mg_connection *c;
   for (c = mgr->conns; c != NULL; c = c->next) {
-    if (c->label[0] != 'S') continue;      // Skip non-stream connections
+    if (c->label[0] != 'S') continue;         // Skip non-stream connections
     if (data == NULL || size == 0) continue;  // Skip on file read error
     mg_printf(c,
               "--foo\r\nContent-Type: image/jpeg\r\n"
diff --git a/examples/dashboard/main.c b/examples/dashboard/main.c
index 922c7b74..b85ca07e 100644
--- a/examples/dashboard/main.c
+++ b/examples/dashboard/main.c
@@ -66,7 +66,8 @@ static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
       c->label[0] = 'W';  // Mark ourselves as a config watcher
       mg_printf(c, "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n");
     } else {
-      mg_http_serve_dir(c, ev_data, "web_root");
+      struct mg_http_serve_opts opts = {.root_dir = "web_root"};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
 }
diff --git a/examples/desktop-server/Makefile b/examples/desktop-server/Makefile
index 632710f2..baa9b5b5 100644
--- a/examples/desktop-server/Makefile
+++ b/examples/desktop-server/Makefile
@@ -1,6 +1,6 @@
 PROG ?= example
 ROOT ?= $(realpath $(CURDIR)/../..)
-DEFS ?= -DMG_ENABLE_LINES=1 -DMG_ENABLE_DIRECTORY_LISTING=1
+DEFS ?= -DMG_ENABLE_LINES=1 -DMG_ENABLE_DIRECTORY_LISTING=1 -DMG_ENABLE_SSI=1
 CFLAGS ?= -I../.. -W -Wall -DMG_ENABLE_IPV6=1 $(DEFS) $(EXTRA)
 VCFLAGS = /nologo /W3 /O2 /I../.. $(DEFS) $(EXTRA)
 VC98 = docker run --rm -e WINEDEBUG=-all -v $(ROOT):$(ROOT) -w $(CURDIR) docker.io/mdashnet/vc98
diff --git a/examples/desktop-server/main.c b/examples/desktop-server/main.c
index 5b4569ca..23da36eb 100644
--- a/examples/desktop-server/main.c
+++ b/examples/desktop-server/main.c
@@ -8,11 +8,13 @@ static const char *s_web_root_dir = ".";
 static const char *s_listening_address = "http://localhost:8000";
 static const char *s_enable_hexdump = "no";
 static const char *s_rewrites = "";
+static const char *s_ssi_pattern = "#.shtml";
 
 static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
   if (ev == MG_EV_HTTP_MSG) {
-    // struct mg_http_message *hm = (struct mg_http_message *) ev_data;
-    mg_http_serve_dir(c, ev_data, s_web_root_dir);
+    struct mg_http_serve_opts opts = {.root_dir = s_web_root_dir,
+                                      .ssi_pattern = s_ssi_pattern};
+    mg_http_serve_dir(c, ev_data, &opts);
   }
   (void) fn_data;
 }
@@ -23,11 +25,12 @@ static void usage(const char *prog) {
           "\nUsage: %s OPTIONS\n"
           "  -D LEVEL  - debug level, from 0 to 4, default: '%s'\n"
           "  -H yes|no - enable traffic hexdump, default: '%s'\n"
+          "  -S GLOB   - glob pattern for SSI files, default: '%s'\n"
           "  -d DIR    - directory to serve, default: '%s'\n"
           "  -l ADDR   - listening address, default: '%s'\n"
           "  -r LIST   - list of URI=DIR,... URI rewrites, default: '%s'\n",
-          MG_VERSION, prog, s_debug_level, s_enable_hexdump, s_web_root_dir,
-          s_listening_address, s_rewrites);
+          MG_VERSION, prog, s_debug_level, s_enable_hexdump, s_ssi_pattern,
+          s_web_root_dir, s_listening_address, s_rewrites);
   exit(EXIT_FAILURE);
 }
 
@@ -44,6 +47,8 @@ int main(int argc, char *argv[]) {
       s_debug_level = argv[++i];
     } else if (strcmp(argv[i], "-H") == 0) {
       s_enable_hexdump = argv[++i];
+    } else if (strcmp(argv[i], "-S") == 0) {
+      s_ssi_pattern = argv[++i];
     } else if (strcmp(argv[i], "-l") == 0) {
       s_listening_address = argv[++i];
     } else if (strcmp(argv[i], "-r") == 0) {
diff --git a/examples/file-upload/main.c b/examples/file-upload/main.c
index 21bc456b..38520846 100644
--- a/examples/file-upload/main.c
+++ b/examples/file-upload/main.c
@@ -12,7 +12,8 @@ static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
     if (mg_http_match_uri(hm, "/upload")) {
       mg_http_upload(c, hm, "/tmp");
     } else {
-      mg_http_serve_dir(c, ev_data, "web_root");
+      struct mg_http_serve_opts opts = {.root_dir = "web_root"};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
 }
diff --git a/examples/http-restful-server/main.c b/examples/http-restful-server/main.c
index cd5236f9..acd6e6b1 100644
--- a/examples/http-restful-server/main.c
+++ b/examples/http-restful-server/main.c
@@ -34,7 +34,8 @@ static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
       mg_http_reply(c, 200, "", "{\"result\": \"%.*s\"}\n", (int) hm->uri.len,
                     hm->uri.ptr);
     } else {
-      mg_http_serve_dir(c, ev_data, s_web_directory);  // Serve static files
+      struct mg_http_serve_opts opts = {.root_dir = s_web_directory};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
   (void) fn_data;
diff --git a/examples/live-log/main.c b/examples/live-log/main.c
index 17df9310..75679e29 100644
--- a/examples/live-log/main.c
+++ b/examples/live-log/main.c
@@ -16,7 +16,8 @@ static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
       c->label[0] = 'L';  // Mark that connection as live log listener
       mg_printf(c, "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n");
     } else {
-      mg_http_serve_dir(c, ev_data, "web_root");
+      struct mg_http_serve_opts opts = {.root_dir = "web_root"};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
 }
diff --git a/examples/multiple-logins/main.c b/examples/multiple-logins/main.c
index 469861d0..e6c64171 100644
--- a/examples/multiple-logins/main.c
+++ b/examples/multiple-logins/main.c
@@ -71,7 +71,8 @@ static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
                            u->token);
       mg_http_printf_chunk(c, "");
     } else {
-      mg_http_serve_dir(c, ev_data, "web_root");
+      struct mg_http_serve_opts opts = {.root_dir = "web_root"};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
 }
diff --git a/examples/video-stream/main.c b/examples/video-stream/main.c
index ab092afd..991c7f3b 100644
--- a/examples/video-stream/main.c
+++ b/examples/video-stream/main.c
@@ -18,7 +18,8 @@ static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
           "Pragma: no-cache\r\nExpires: Thu, 01 Dec 1994 16:00:00 GMT\r\n"
           "Content-Type: multipart/x-mixed-replace; boundary=--foo\r\n\r\n");
     } else {
-      mg_http_serve_dir(c, ev_data, "web_root");
+      struct mg_http_serve_opts opts = {.root_dir = "web_root"};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   }
 }
@@ -35,7 +36,7 @@ static void broadcast_mjpeg_frame(struct mg_mgr *mgr) {
   char *data = mg_file_read(path);  // Read next file
   struct mg_connection *c;
   for (c = mgr->conns; c != NULL; c = c->next) {
-    if (c->label[0] != 'S') continue;      // Skip non-stream connections
+    if (c->label[0] != 'S') continue;         // Skip non-stream connections
     if (data == NULL || size == 0) continue;  // Skip on file read error
     mg_printf(c,
               "--foo\r\nContent-Type: image/jpeg\r\n"
diff --git a/examples/websocket-server/main.c b/examples/websocket-server/main.c
index f9b76751..d9df7cc0 100644
--- a/examples/websocket-server/main.c
+++ b/examples/websocket-server/main.c
@@ -27,7 +27,8 @@ static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
       mg_http_reply(c, 200, "", "{\"result\": %d}\n", 123);
     } else {
       // Serve static files
-      mg_http_serve_dir(c, ev_data, s_web_directory);
+      struct mg_http_serve_opts opts = {.root_dir = s_web_directory};
+      mg_http_serve_dir(c, ev_data, &opts);
     }
   } else if (ev == MG_EV_WS_MSG) {
     // Got websocket frame. Received data is wm->data. Echo it back!
diff --git a/mongoose.c b/mongoose.c
index 57b5ed2b..a7dc9c10 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -422,6 +422,7 @@ void mg_error(struct mg_connection *c, const char *fmt, ...) {
 
 
 
+
 struct http_data {
   void *old_pfn_data;  // Previous pfn_data
   FILE *fp;            // For static file serving
@@ -1009,7 +1010,7 @@ static void listdir(struct mg_connection *c, struct mg_http_message *hm,
 #endif
 
 void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
-                       const struct mg_http_serve_opts *opts) {
+                       struct mg_http_serve_opts *opts) {
   char path[PATH_MAX + 2], root[sizeof(path) - 2], real[sizeof(path) - 2];
   path[0] = root[0] = real[0] = '\0';
   if (realpath(opts->root_dir, root) == NULL)
@@ -1028,12 +1029,22 @@ void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
     // LOG(LL_INFO, ("[%s] [%s] [%s] [%s]", dir, root, path, real));
     if (mg_is_dir(real)) {
       strncat(real, "/index.html", sizeof(real) - strlen(real) - 1);
+      real[sizeof(real) - 1] = '\0';
       is_index = true;
     }
     if (strlen(real) < strlen(root) || memcmp(real, root, strlen(root)) != 0) {
       mg_http_reply(c, 404, "", "Not found %.*s\n", hm->uri.len, hm->uri.ptr);
     } else {
       FILE *fp = fopen(real, "r");
+#if MG_ENABLE_SSI
+      if (is_index && fp == NULL) {
+        char *p = real + strlen(real);
+        while (p > real && p[-1] != '/') p--;
+        strncpy(p, "index.shtml", &real[sizeof(real)] - p - 2);
+        real[sizeof(real) - 1] = '\0';
+        fp = fopen(real, "r");
+      }
+#endif
 #if MG_ENABLE_HTTP_DEBUG_ENDPOINT
       snprintf(c->label, sizeof(c->label) - 1, "<-F %s", real);
 #endif
@@ -1042,6 +1053,12 @@ void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
         listdir(c, hm, real);
 #else
         mg_http_reply(c, 403, "", "%s", "Directory listing not supported");
+#endif
+#if MG_ENABLE_SSI
+      } else if (opts->ssi_pattern != NULL &&
+                 mg_globmatch(opts->ssi_pattern, strlen(opts->ssi_pattern),
+                              real, strlen(real))) {
+        mg_http_serve_ssi(c, root, real);
 #endif
       } else {
         mg_http_serve_file(c, hm, real, guess_content_type(real));
@@ -2984,6 +3001,93 @@ void mg_mgr_poll(struct mg_mgr *mgr, int ms) {
 }
 #endif
 
+#ifdef MG_ENABLE_LINES
+#line 1 "src/ssi.c"
+#endif
+
+
+
+#ifndef MG_MAX_SSI_DEPTH
+#define MG_MAX_SSI_DEPTH 5
+#endif
+
+#if MG_ENABLE_SSI
+static char *mg_ssi(const char *path, const char *root, int depth) {
+  struct mg_iobuf b = {NULL, 0, 0};
+  FILE *fp = fopen(path, "rb");
+  if (fp != NULL) {
+    char buf[BUFSIZ], arg[sizeof(buf)];
+    int ch, intag = 0;
+    size_t len = 0, align = MG_IO_SIZE;
+    while ((ch = fgetc(fp)) != EOF) {
+      if (intag && ch == '>' && buf[len - 1] == '-' && buf[len - 2] == '-') {
+        buf[len++] = ch & 0xff;
+        if (sscanf(buf, "<!--#include file=\"%[^\"]", arg)) {
+          char tmp[PATH_MAX], *p = (char *) path + strlen(path), *data;
+          while (p > path && p[-1] != MG_DIRSEP && p[-1] != '/') p--;
+          snprintf(tmp, sizeof(tmp), "%.*s%s", (int) (p - path), path, arg);
+          if (depth < MG_MAX_SSI_DEPTH &&
+              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
+            mg_iobuf_append(&b, data, strlen(data), align);
+            free(data);
+          } else {
+            LOG(LL_ERROR, ("%s: file=%s error or too deep", path, arg));
+          }
+        } else if (sscanf(buf, "<!--#include virtual=\"%[^\"]", arg)) {
+          char tmp[PATH_MAX], *data;
+          snprintf(tmp, sizeof(tmp), "%s%s", root, arg);
+          if (depth < MG_MAX_SSI_DEPTH &&
+              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
+            mg_iobuf_append(&b, data, strlen(data), align);
+            free(data);
+          } else {
+            LOG(LL_ERROR, ("%s: virtual=%s error or too deep", path, arg));
+          }
+        } else {
+          // Unknown SSI tag
+          LOG(LL_INFO, ("Unknown SSI tag: %.*s", (int) len, buf));
+          mg_iobuf_append(&b, buf, len, align);
+        }
+        intag = 0;
+        len = 0;
+      } else if (ch == '<') {
+        intag = 1;
+        if (len > 0) mg_iobuf_append(&b, buf, len, align);
+        len = 0;
+        buf[len++] = ch & 0xff;
+      } else if (intag) {
+        if (len == 5 && strncmp(buf, "<!--#", 5) != 0) {
+          intag = 0;
+        } else if (len >= sizeof(buf) - 2) {
+          LOG(LL_ERROR, ("%s: SSI tag is too large", path));
+          len = 0;
+        }
+        buf[len++] = ch & 0xff;
+      } else {
+        buf[len++] = ch & 0xff;
+        if (len >= sizeof(buf)) {
+          mg_iobuf_append(&b, buf, len, align);
+          len = 0;
+        }
+      }
+    }
+    if (len > 0) mg_iobuf_append(&b, buf, len, align);
+    if (b.len > 0) mg_iobuf_append(&b, "", 1, align);  // nul-terminate
+    fclose(fp);
+  }
+  (void) depth;
+  (void) root;
+  return (char *) b.buf;
+}
+
+void mg_http_serve_ssi(struct mg_connection *c, const char *root,
+                       const char *fullpath) {
+  char *data = mg_ssi(fullpath, root, 0);
+  mg_http_reply(c, 200, "", "%s", data == NULL ? "" : data);
+  free(data);
+}
+#endif
+
 #ifdef MG_ENABLE_LINES
 #line 1 "src/str.c"
 #endif
diff --git a/mongoose.h b/mongoose.h
index ca7f6834..a6624844 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -296,6 +296,10 @@ typedef int socklen_t;
 #define MG_ENABLE_FS 1
 #endif
 
+#ifndef MG_ENABLE_SSI
+#define MG_ENABLE_SSI 0
+#endif
+
 #ifndef MG_ENABLE_IPV6
 #define MG_ENABLE_IPV6 0
 #endif
@@ -667,8 +671,8 @@ struct mg_http_message {
 
 // Parameter for mg_http_serve_dir()
 struct mg_http_serve_opts {
-  const char *root_dir;
-  const char *ssi_pattern;
+  const char *root_dir;     // Web root directory, must be non-NULL
+  const char *ssi_pattern;  // SSI filename pattern, e.g. #.shtml
 };
 
 int mg_http_parse(const char *s, size_t len, struct mg_http_message *);
@@ -680,7 +684,7 @@ struct mg_connection *mg_http_listen(struct mg_mgr *, const char *url,
 struct mg_connection *mg_http_connect(struct mg_mgr *, const char *url,
                                       mg_event_handler_t fn, void *fn_data);
 void mg_http_serve_dir(struct mg_connection *, struct mg_http_message *hm,
-                       const struct mg_http_serve_opts *);
+                       struct mg_http_serve_opts *);
 void mg_http_serve_file(struct mg_connection *, struct mg_http_message *,
                         const char *, const char *mime);
 void mg_http_reply(struct mg_connection *, int status_code, const char *headers,
@@ -696,6 +700,10 @@ int mg_http_upload(struct mg_connection *, struct mg_http_message *hm,
 void mg_http_bauth(struct mg_connection *, const char *user, const char *pass);
 
 
+void mg_http_serve_ssi(struct mg_connection *c, const char *root,
+                       const char *fullpath);
+
+
 
 struct mg_tls_opts {
   const char *ca;        // CA certificate file. For both listeners and clients
diff --git a/src/config.h b/src/config.h
index 7b845737..a83a55b2 100644
--- a/src/config.h
+++ b/src/config.h
@@ -22,6 +22,10 @@
 #define MG_ENABLE_FS 1
 #endif
 
+#ifndef MG_ENABLE_SSI
+#define MG_ENABLE_SSI 0
+#endif
+
 #ifndef MG_ENABLE_IPV6
 #define MG_ENABLE_IPV6 0
 #endif
diff --git a/src/http.c b/src/http.c
index 40a7539b..364cf956 100644
--- a/src/http.c
+++ b/src/http.c
@@ -4,6 +4,7 @@
 #include "log.h"
 #include "net.h"
 #include "private.h"
+#include "ssi.h"
 #include "util.h"
 #include "version.h"
 #include "ws.h"
@@ -595,7 +596,7 @@ static void listdir(struct mg_connection *c, struct mg_http_message *hm,
 #endif
 
 void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
-                       const struct mg_http_serve_opts *opts) {
+                       struct mg_http_serve_opts *opts) {
   char path[PATH_MAX + 2], root[sizeof(path) - 2], real[sizeof(path) - 2];
   path[0] = root[0] = real[0] = '\0';
   if (realpath(opts->root_dir, root) == NULL)
@@ -614,12 +615,22 @@ void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
     // LOG(LL_INFO, ("[%s] [%s] [%s] [%s]", dir, root, path, real));
     if (mg_is_dir(real)) {
       strncat(real, "/index.html", sizeof(real) - strlen(real) - 1);
+      real[sizeof(real) - 1] = '\0';
       is_index = true;
     }
     if (strlen(real) < strlen(root) || memcmp(real, root, strlen(root)) != 0) {
       mg_http_reply(c, 404, "", "Not found %.*s\n", hm->uri.len, hm->uri.ptr);
     } else {
       FILE *fp = fopen(real, "r");
+#if MG_ENABLE_SSI
+      if (is_index && fp == NULL) {
+        char *p = real + strlen(real);
+        while (p > real && p[-1] != '/') p--;
+        strncpy(p, "index.shtml", &real[sizeof(real)] - p - 2);
+        real[sizeof(real) - 1] = '\0';
+        fp = fopen(real, "r");
+      }
+#endif
 #if MG_ENABLE_HTTP_DEBUG_ENDPOINT
       snprintf(c->label, sizeof(c->label) - 1, "<-F %s", real);
 #endif
@@ -628,6 +639,12 @@ void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
         listdir(c, hm, real);
 #else
         mg_http_reply(c, 403, "", "%s", "Directory listing not supported");
+#endif
+#if MG_ENABLE_SSI
+      } else if (opts->ssi_pattern != NULL &&
+                 mg_globmatch(opts->ssi_pattern, strlen(opts->ssi_pattern),
+                              real, strlen(real))) {
+        mg_http_serve_ssi(c, root, real);
 #endif
       } else {
         mg_http_serve_file(c, hm, real, guess_content_type(real));
diff --git a/src/http.h b/src/http.h
index 4272e5d3..2406af6a 100644
--- a/src/http.h
+++ b/src/http.h
@@ -21,8 +21,8 @@ struct mg_http_message {
 
 // Parameter for mg_http_serve_dir()
 struct mg_http_serve_opts {
-  const char *root_dir;
-  const char *ssi_pattern;
+  const char *root_dir;     // Web root directory, must be non-NULL
+  const char *ssi_pattern;  // SSI filename pattern, e.g. #.shtml
 };
 
 int mg_http_parse(const char *s, size_t len, struct mg_http_message *);
@@ -34,7 +34,7 @@ struct mg_connection *mg_http_listen(struct mg_mgr *, const char *url,
 struct mg_connection *mg_http_connect(struct mg_mgr *, const char *url,
                                       mg_event_handler_t fn, void *fn_data);
 void mg_http_serve_dir(struct mg_connection *, struct mg_http_message *hm,
-                       const struct mg_http_serve_opts *);
+                       struct mg_http_serve_opts *);
 void mg_http_serve_file(struct mg_connection *, struct mg_http_message *,
                         const char *, const char *mime);
 void mg_http_reply(struct mg_connection *, int status_code, const char *headers,
diff --git a/src/ssi.c b/src/ssi.c
new file mode 100644
index 00000000..b2b822e2
--- /dev/null
+++ b/src/ssi.c
@@ -0,0 +1,83 @@
+#include "log.h"
+#include "ssi.h"
+
+#ifndef MG_MAX_SSI_DEPTH
+#define MG_MAX_SSI_DEPTH 5
+#endif
+
+#if MG_ENABLE_SSI
+static char *mg_ssi(const char *path, const char *root, int depth) {
+  struct mg_iobuf b = {NULL, 0, 0};
+  FILE *fp = fopen(path, "rb");
+  if (fp != NULL) {
+    char buf[BUFSIZ], arg[sizeof(buf)];
+    int ch, intag = 0;
+    size_t len = 0, align = MG_IO_SIZE;
+    while ((ch = fgetc(fp)) != EOF) {
+      if (intag && ch == '>' && buf[len - 1] == '-' && buf[len - 2] == '-') {
+        buf[len++] = ch & 0xff;
+        if (sscanf(buf, "<!--#include file=\"%[^\"]", arg)) {
+          char tmp[PATH_MAX], *p = (char *) path + strlen(path), *data;
+          while (p > path && p[-1] != MG_DIRSEP && p[-1] != '/') p--;
+          snprintf(tmp, sizeof(tmp), "%.*s%s", (int) (p - path), path, arg);
+          if (depth < MG_MAX_SSI_DEPTH &&
+              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
+            mg_iobuf_append(&b, data, strlen(data), align);
+            free(data);
+          } else {
+            LOG(LL_ERROR, ("%s: file=%s error or too deep", path, arg));
+          }
+        } else if (sscanf(buf, "<!--#include virtual=\"%[^\"]", arg)) {
+          char tmp[PATH_MAX], *data;
+          snprintf(tmp, sizeof(tmp), "%s%s", root, arg);
+          if (depth < MG_MAX_SSI_DEPTH &&
+              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
+            mg_iobuf_append(&b, data, strlen(data), align);
+            free(data);
+          } else {
+            LOG(LL_ERROR, ("%s: virtual=%s error or too deep", path, arg));
+          }
+        } else {
+          // Unknown SSI tag
+          LOG(LL_INFO, ("Unknown SSI tag: %.*s", (int) len, buf));
+          mg_iobuf_append(&b, buf, len, align);
+        }
+        intag = 0;
+        len = 0;
+      } else if (ch == '<') {
+        intag = 1;
+        if (len > 0) mg_iobuf_append(&b, buf, len, align);
+        len = 0;
+        buf[len++] = ch & 0xff;
+      } else if (intag) {
+        if (len == 5 && strncmp(buf, "<!--#", 5) != 0) {
+          intag = 0;
+        } else if (len >= sizeof(buf) - 2) {
+          LOG(LL_ERROR, ("%s: SSI tag is too large", path));
+          len = 0;
+        }
+        buf[len++] = ch & 0xff;
+      } else {
+        buf[len++] = ch & 0xff;
+        if (len >= sizeof(buf)) {
+          mg_iobuf_append(&b, buf, len, align);
+          len = 0;
+        }
+      }
+    }
+    if (len > 0) mg_iobuf_append(&b, buf, len, align);
+    if (b.len > 0) mg_iobuf_append(&b, "", 1, align);  // nul-terminate
+    fclose(fp);
+  }
+  (void) depth;
+  (void) root;
+  return (char *) b.buf;
+}
+
+void mg_http_serve_ssi(struct mg_connection *c, const char *root,
+                       const char *fullpath) {
+  char *data = mg_ssi(fullpath, root, 0);
+  mg_http_reply(c, 200, "", "%s", data == NULL ? "" : data);
+  free(data);
+}
+#endif
diff --git a/src/ssi.h b/src/ssi.h
new file mode 100644
index 00000000..024abb3c
--- /dev/null
+++ b/src/ssi.h
@@ -0,0 +1,4 @@
+#pragma once
+#include "http.h"
+void mg_http_serve_ssi(struct mg_connection *c, const char *root,
+                       const char *fullpath);
diff --git a/test/data/ssi/f1.txt b/test/data/ssi/f1.txt
new file mode 100644
index 00000000..11ac5613
--- /dev/null
+++ b/test/data/ssi/f1.txt
@@ -0,0 +1 @@
+this is f1
diff --git a/test/data/ssi/index.shtml b/test/data/ssi/index.shtml
new file mode 100644
index 00000000..e8e06e13
--- /dev/null
+++ b/test/data/ssi/index.shtml
@@ -0,0 +1,3 @@
+this is index
+<!--#include file="nested.shtml" -->
+<!--#include file="recurse.shtml" -->
diff --git a/test/data/ssi/nested.shtml b/test/data/ssi/nested.shtml
new file mode 100644
index 00000000..898c73b8
--- /dev/null
+++ b/test/data/ssi/nested.shtml
@@ -0,0 +1,3 @@
+this is nested
+<!--#include virtual="/notexist.txt"-->
+<!--#include virtual="/ssi/f1.txt"-->
diff --git a/test/data/ssi/recurse.shtml b/test/data/ssi/recurse.shtml
new file mode 100644
index 00000000..87e7c3a9
--- /dev/null
+++ b/test/data/ssi/recurse.shtml
@@ -0,0 +1,2 @@
+<!--#include file="recurse.shtml"-->
+recurse
diff --git a/test/unit_test.c b/test/unit_test.c
index 7fa27640..4f2168a6 100644
--- a/test/unit_test.c
+++ b/test/unit_test.c
@@ -349,7 +349,7 @@ static void eh1(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
       struct mg_http_serve_opts opts = {".", NULL};
       mg_http_serve_dir(c, hm, &opts);
     } else {
-      struct mg_http_serve_opts opts = {"./test/data", NULL};
+      struct mg_http_serve_opts opts = {"./test/data", "#.shtml"};
       mg_http_serve_dir(c, hm, &opts);
     }
   } else if (ev == MG_EV_WS_MSG) {
@@ -477,6 +477,17 @@ static void test_http_server(void) {
                "Content-Length: 4\r\n\r\nkuku") == 200);
   ASSERT(cmpbody(buf, "kuku") == 0);
 
+  ASSERT(fetch(&mgr, buf, url, "GET /ssi HTTP/1.1\r\n\r\n") == 200);
+  ASSERT(cmpbody(buf,
+                 "this is index\n"
+                 "this is nested\n\n"
+                 "this is f1\n\n\n\n"
+                 "recurse\n\n"
+                 "recurse\n\n"
+                 "recurse\n\n"
+                 "recurse\n\n"
+                 "recurse\n\n") == 0);
+
   ASSERT(fetch(&mgr, buf, url, "GET /badroot HTTP/1.0\r\n\n") == 400);
 #if MG_ARCH == MG_ARCH_WIN32
   ASSERT(cmpbody(buf, "Bad web root [Z:\\BAAADDD!]\n") == 0);