diff --git a/mongoose.c b/mongoose.c
index d75ecd65..e029e40e 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -671,9 +671,9 @@ static void restore_http_cb(struct mg_connection *c) {
   free(d);
 }
 
-char *mg_http_etag(char *buf, size_t len, struct stat *st) {
-  snprintf(buf, len, "\"%lx.%lu\"", (unsigned long) st->st_mtime,
-           (unsigned long) st->st_size);
+char *mg_http_etag(char *buf, size_t len, mg_stat_t *st) {
+  snprintf(buf, len, "\"%lx." MG_INT64_FMT "\"", (unsigned long) st->st_mtime,
+           (int64_t) st->st_size);
   return buf;
 }
 
@@ -785,10 +785,10 @@ static const char *guess_content_type(const char *filename) {
 void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
                         const char *path, const char *mime, const char *hdrs) {
   struct mg_str *inm = mg_http_get_header(hm, "If-None-Match");
-  struct stat st;
+  mg_stat_t st;
   FILE *fp = fopen(path, "rb");
   char etag[64];
-  if (fp == NULL || stat(path, &st) != 0 ||
+  if (fp == NULL || mg_stat(path, &st) != 0 ||
       mg_http_etag(etag, sizeof(etag), &st) != etag) {
     mg_http_reply(c, 404, "", "%s", "Not found\n");
   } else if (inm != NULL && mg_vcasecmp(inm, etag) == 0) {
@@ -797,8 +797,8 @@ void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
   } else {
     mg_printf(c,
               "HTTP/1.1 200 OK\r\nContent-Type: %s\r\n"
-              "Etag: %s\r\nContent-Length: %lu\r\n%s\r\n",
-              mime, etag, (unsigned long) st.st_size, hdrs ? hdrs : "");
+              "Etag: %s\r\nContent-Length: " MG_INT64_FMT "\r\n%s\r\n",
+              mime, etag, (int64_t) st.st_size, hdrs ? hdrs : "");
     if (mg_vcasecmp(&hm->method, "HEAD") == 0) {
       fclose(fp);
     } else {
@@ -949,7 +949,7 @@ struct dirent *readdir(DIR *d) {
 #endif
 
 static void printdirentry(struct mg_connection *c, struct mg_http_message *hm,
-                          const char *name, struct stat *stp) {
+                          const char *name, mg_stat_t *stp) {
   char size[64], mod[64];  //, path[PATH_MAX];
   int is_dir = S_ISDIR(stp->st_mode);
   const char *slash = is_dir ? "/" : "";
@@ -997,11 +997,11 @@ static void listdir(struct mg_connection *c, struct mg_http_message *hm,
         "<tr><td colspan=\"3\"><hr></td></tr></thead><tbody>\n",
         (int) hm->uri.len, hm->uri.ptr, (int) hm->uri.len, hm->uri.ptr);
     while ((dp = readdir(dirp)) != NULL) {
-      struct stat st;
+      mg_stat_t st;
       // Do not show current dir and hidden files
       if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) continue;
       snprintf(path, sizeof(path), "%s/%s", dir, dp->d_name);
-      if (stat(path, &st) != 0) {
+      if (mg_stat(path, &st) != 0) {
         LOG(LL_ERROR, ("%lu stat(%s): %d", c->id, path, errno));
         continue;
       }
@@ -3711,6 +3711,7 @@ struct mg_str mg_url_pass(const char *url) {
 #endif
 
 
+
 #if MG_ENABLE_FS
 size_t mg_file_size(const char *path) {
 #if MG_ARCH == MG_ARCH_FREERTOS
diff --git a/mongoose.h b/mongoose.h
index 9e9da925..61114449 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -121,6 +121,7 @@
 #include <dirent.h>
 #include <netdb.h>
 #define MG_DIRSEP '/'
+#define MG_INT64_FMT "%lld"
 
 #endif
 
@@ -133,6 +134,7 @@
 #include <stdbool.h>
 #include <sys/time.h>
 #define MG_DIRSEP '/'
+#define MG_INT64_FMT "%lld"
 
 #endif
 
@@ -146,6 +148,7 @@
 #include <FreeRTOS_Sockets.h>
 #include <stdbool.h>
 
+#define MG_INT64_FMT "%lld"
 #define MG_DIRSEP '/'
 #define IPPROTO_TCP FREERTOS_IPPROTO_TCP
 #define IPPROTO_UDP FREERTOS_IPPROTO_UDP
@@ -206,6 +209,7 @@ static inline int ff_vfprintf(FF_FILE *fp, const char *fmt, va_list ap) {
 
 #include <arpa/inet.h>
 #include <dirent.h>
+#include <inttypes.h>
 #include <netdb.h>
 #include <netinet/tcp.h>
 #include <signal.h>
@@ -217,6 +221,7 @@ static inline int ff_vfprintf(FF_FILE *fp, const char *fmt, va_list ap) {
 #include <unistd.h>
 #define MG_DIRSEP '/'
 #define MG_ENABLE_POSIX 1
+#define MG_INT64_FMT "%" PRId64
 
 #endif
 
@@ -273,6 +278,8 @@ typedef int socklen_t;
 #define S_ISDIR(x) (((x) &_S_IFMT) == _S_IFDIR)
 #endif
 
+#define MG_INT64_FMT "%I64d"
+
 #endif
 
 
@@ -432,6 +439,16 @@ double mg_time(void);
 unsigned long mg_millis(void);
 void mg_usleep(unsigned long usecs);
 
+#if MG_ENABLE_FS
+#ifdef _WIN32
+typedef struct _stati64 mg_stat_t;
+#define mg_stat(a, b) _stati64((a), (b))
+#else
+typedef struct stat mg_stat_t;
+#define mg_stat(a, b) stat((a), (b))
+#endif
+#endif
+
 #define mg_htons(x) mg_ntohs(x)
 #define mg_htonl(x) mg_ntohl(x)
 
diff --git a/src/arch_esp32.h b/src/arch_esp32.h
index ea503313..a50711b3 100644
--- a/src/arch_esp32.h
+++ b/src/arch_esp32.h
@@ -5,5 +5,6 @@
 #include <dirent.h>
 #include <netdb.h>
 #define MG_DIRSEP '/'
+#define MG_INT64_FMT "%lld"
 
 #endif
diff --git a/src/arch_esp8266.h b/src/arch_esp8266.h
index 243b5831..18834717 100644
--- a/src/arch_esp8266.h
+++ b/src/arch_esp8266.h
@@ -8,5 +8,6 @@
 #include <stdbool.h>
 #include <sys/time.h>
 #define MG_DIRSEP '/'
+#define MG_INT64_FMT "%lld"
 
 #endif
diff --git a/src/arch_freertos.h b/src/arch_freertos.h
index f4ec5bed..64fbb9ac 100644
--- a/src/arch_freertos.h
+++ b/src/arch_freertos.h
@@ -9,6 +9,7 @@
 #include <FreeRTOS_Sockets.h>
 #include <stdbool.h>
 
+#define MG_INT64_FMT "%lld"
 #define MG_DIRSEP '/'
 #define IPPROTO_TCP FREERTOS_IPPROTO_TCP
 #define IPPROTO_UDP FREERTOS_IPPROTO_UDP
diff --git a/src/arch_unix.h b/src/arch_unix.h
index 81f11dae..b3dbb352 100644
--- a/src/arch_unix.h
+++ b/src/arch_unix.h
@@ -6,6 +6,7 @@
 
 #include <arpa/inet.h>
 #include <dirent.h>
+#include <inttypes.h>
 #include <netdb.h>
 #include <netinet/tcp.h>
 #include <signal.h>
@@ -17,5 +18,6 @@
 #include <unistd.h>
 #define MG_DIRSEP '/'
 #define MG_ENABLE_POSIX 1
+#define MG_INT64_FMT "%" PRId64
 
 #endif
diff --git a/src/arch_win32.h b/src/arch_win32.h
index 648f2cab..c78ebd4a 100644
--- a/src/arch_win32.h
+++ b/src/arch_win32.h
@@ -52,4 +52,6 @@ typedef int socklen_t;
 #define S_ISDIR(x) (((x) &_S_IFMT) == _S_IFDIR)
 #endif
 
+#define MG_INT64_FMT "%I64d"
+
 #endif
diff --git a/src/http.c b/src/http.c
index 4851ad10..a2efca6d 100644
--- a/src/http.c
+++ b/src/http.c
@@ -251,9 +251,9 @@ static void restore_http_cb(struct mg_connection *c) {
   free(d);
 }
 
-char *mg_http_etag(char *buf, size_t len, struct stat *st) {
-  snprintf(buf, len, "\"%lx.%lu\"", (unsigned long) st->st_mtime,
-           (unsigned long) st->st_size);
+char *mg_http_etag(char *buf, size_t len, mg_stat_t *st) {
+  snprintf(buf, len, "\"%lx." MG_INT64_FMT "\"", (unsigned long) st->st_mtime,
+           (int64_t) st->st_size);
   return buf;
 }
 
@@ -365,10 +365,10 @@ static const char *guess_content_type(const char *filename) {
 void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
                         const char *path, const char *mime, const char *hdrs) {
   struct mg_str *inm = mg_http_get_header(hm, "If-None-Match");
-  struct stat st;
+  mg_stat_t st;
   FILE *fp = fopen(path, "rb");
   char etag[64];
-  if (fp == NULL || stat(path, &st) != 0 ||
+  if (fp == NULL || mg_stat(path, &st) != 0 ||
       mg_http_etag(etag, sizeof(etag), &st) != etag) {
     mg_http_reply(c, 404, "", "%s", "Not found\n");
   } else if (inm != NULL && mg_vcasecmp(inm, etag) == 0) {
@@ -377,8 +377,8 @@ void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
   } else {
     mg_printf(c,
               "HTTP/1.1 200 OK\r\nContent-Type: %s\r\n"
-              "Etag: %s\r\nContent-Length: %lu\r\n%s\r\n",
-              mime, etag, (unsigned long) st.st_size, hdrs ? hdrs : "");
+              "Etag: %s\r\nContent-Length: " MG_INT64_FMT "\r\n%s\r\n",
+              mime, etag, (int64_t) st.st_size, hdrs ? hdrs : "");
     if (mg_vcasecmp(&hm->method, "HEAD") == 0) {
       fclose(fp);
     } else {
@@ -529,7 +529,7 @@ struct dirent *readdir(DIR *d) {
 #endif
 
 static void printdirentry(struct mg_connection *c, struct mg_http_message *hm,
-                          const char *name, struct stat *stp) {
+                          const char *name, mg_stat_t *stp) {
   char size[64], mod[64];  //, path[PATH_MAX];
   int is_dir = S_ISDIR(stp->st_mode);
   const char *slash = is_dir ? "/" : "";
@@ -577,11 +577,11 @@ static void listdir(struct mg_connection *c, struct mg_http_message *hm,
         "<tr><td colspan=\"3\"><hr></td></tr></thead><tbody>\n",
         (int) hm->uri.len, hm->uri.ptr, (int) hm->uri.len, hm->uri.ptr);
     while ((dp = readdir(dirp)) != NULL) {
-      struct stat st;
+      mg_stat_t st;
       // Do not show current dir and hidden files
       if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) continue;
       snprintf(path, sizeof(path), "%s/%s", dir, dp->d_name);
-      if (stat(path, &st) != 0) {
+      if (mg_stat(path, &st) != 0) {
         LOG(LL_ERROR, ("%lu stat(%s): %d", c->id, path, errno));
         continue;
       }
diff --git a/src/util.h b/src/util.h
index 9e837e18..fe4ecf24 100644
--- a/src/util.h
+++ b/src/util.h
@@ -23,6 +23,16 @@ double mg_time(void);
 unsigned long mg_millis(void);
 void mg_usleep(unsigned long usecs);
 
+#if MG_ENABLE_FS
+#ifdef _WIN32
+typedef struct _stati64 mg_stat_t;
+#define mg_stat(a, b) _stati64((a), (b))
+#else
+typedef struct stat mg_stat_t;
+#define mg_stat(a, b) stat((a), (b))
+#endif
+#endif
+
 #define mg_htons(x) mg_ntohs(x)
 #define mg_htonl(x) mg_ntohl(x)
 
diff --git a/test/unit_test.c b/test/unit_test.c
index 5db4ea35..b88db0dc 100644
--- a/test/unit_test.c
+++ b/test/unit_test.c
@@ -451,7 +451,7 @@ static void test_http_server(void) {
   struct mg_mgr mgr;
   const char *url = "http://127.0.0.1:12346";
   char buf[FETCH_BUF_SIZE];
-  struct stat st;
+  mg_stat_t st;
 
   mg_mgr_init(&mgr);
   mg_http_listen(&mgr, url, eh1, NULL);
@@ -463,9 +463,9 @@ static void test_http_server(void) {
   ASSERT(cmpbody(buf, "hello\n") == 0);
 
   {
-    extern char *mg_http_etag(char *, size_t, struct stat *);
+    extern char *mg_http_etag(char *, size_t, mg_stat_t *);
     char etag[100];
-    ASSERT(stat("./test/data/a.txt", &st) == 0);
+    ASSERT(mg_stat("./test/data/a.txt", &st) == 0);
     ASSERT(mg_http_etag(etag, sizeof(etag), &st) == etag);
     ASSERT(fetch(&mgr, buf, url, "GET /a.txt HTTP/1.0\nIf-None-Match: %s\n\n",
                  etag) == 304);