diff --git a/mongoose.c b/mongoose.c
index e0485eec..70471ada 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -10591,6 +10591,7 @@ void mg_tcpip_mapip(struct mg_connection *c, struct mg_addr *ip) {
 
 
 
+
 #ifndef MG_OTA_MAX_URL_LEN
 #define MG_OTA_MAX_URL_LEN 256
 #endif
@@ -10611,6 +10612,17 @@ static struct mg_ota_state {
 
 static void s_firmware_fn(struct mg_connection *c, int ev, void *ev_data);
 
+static bool s_tls_init(struct mg_connection *c, const char *url) {
+  struct mg_tls_opts opts = {
+      .ca = mg_str(MG_OTA_TLS_CA), .name = mg_url_host(url)};
+  if (opts.ca.len == 0) {
+    mg_error(c, "MG_OTA_TLS_CA is not configured");
+  } else {
+    mg_tls_init(c, &opts);
+  }
+  return c->is_tls_hs != 0 && !c->is_closing;
+}
+
 #if MG_ENABLE_CUSTOM_DEVICE_ID
 #else
 void mg_ota_device_id(char *buf, size_t len) {
@@ -10643,6 +10655,11 @@ void mg_ota_device_id(char *buf, size_t len) {
 
 static void s_version_fn(struct mg_connection *c, int ev, void *ev_data) {
   uint64_t expiration = *(uint64_t *) c->data;
+  if (s_ota == NULL) {
+    c->fn = NULL;
+    c->is_closing = 1;
+    return;
+  }
   if (ev == MG_EV_POLL) {
     if (mg_millis() > expiration) mg_error(c, "Metadata timeout");
   } else if (ev == MG_EV_CONNECT) {
@@ -10650,6 +10667,9 @@ static void s_version_fn(struct mg_connection *c, int ev, void *ev_data) {
     struct mg_str host = mg_url_host(s_ota->json_url);
     const char *uri = mg_url_uri(s_ota->json_url);
     const char *sep = strchr(uri, '?') == NULL ? "?" : "&";
+    if (mg_url_is_ssl(s_ota->json_url)) {
+      if (!s_tls_init(c, s_ota->json_url)) return;
+    }
     mg_ota_device_id(id, sizeof(id));
     id[sizeof(id) - 1] = '\0';
     mg_printf(
@@ -10715,10 +10735,18 @@ static void status_fn_2(struct mg_connection *c, const char *errmsg) {
 
 static void s_firmware_fn(struct mg_connection *c, int ev, void *ev_data) {
   uint64_t expiration = *(uint64_t *) c->data;
+  if (s_ota == NULL) {
+    c->fn = NULL;
+    c->is_closing = 1;
+    return;
+  }
   if (ev == MG_EV_POLL) {
     if (mg_millis() > expiration) mg_error(c, "OTA timeout");
   } else if (ev == MG_EV_CONNECT) {
     struct mg_str host = mg_url_host(s_ota->url);
+    if (mg_url_is_ssl(s_ota->url)) {
+      if (!s_tls_init(c, s_ota->url)) return;
+    }
     mg_printf(c,
               "GET %s HTTP/1.1\r\n"
               "Host: %.*s\r\n"
diff --git a/mongoose.h b/mongoose.h
index d3f9856c..4f947b25 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -4628,7 +4628,7 @@ extern void mg_mqtt_poll(struct mg_mgr *);
 //
 // This is a low-level OTA API, not intended to be called directly by users.
 // Users are provided with a higher-level API:
-// - defining MG_OTA_URL enables HTTP pull-based updates
+// - defining MG_OTA_URL enables HTTP or HTTPS pull-based updates
 // - mg_http_start_ota() enables push-based updates
 //
 // However, it is possible to use the mg_ota_* API directly. Below is the
@@ -4775,8 +4775,10 @@ enum {
     }                                                              \
   } while (0)
 
-// Pull-based OTA over HTTP. Fetches metadata_url, which must return a JSON
-// object like: { "version": "1.2.3", "url": "FIRMWARE_URL", "size": 324645 }
+// Pull-based OTA over HTTP or HTTPS. If it's HTTPS, MG_OTA_TLS_CA
+// needs to be defined. Fetches metadata_url, which must
+// return a JSON object like:
+// { "version": "1.2.3", "url": "FIRMWARE_URL", "size": 324645 }
 // If the server version differs from MG_OTA_FIRMWARE_VERSION, downloads
 // FIRMWARE_URL and performs the OTA update. fn is called on every outcome:
 // NULL on successful flash, "Same version" when already up to date, or an
@@ -4786,12 +4788,18 @@ void mg_ota_url_check(struct mg_mgr *mgr, const char *metadata_url,
                       void (*fn)(const char *error_message));
 
 // Firmware info URL for mg_ota_poll() which calls mg_ota_url_check().
-// Example:  "http://mongoose.ws/ota/u/0/ota.json". See http://mongoose.ws/ota/
+// Example: "http://mongoose.ws/ota/u/0/ota.json". See http://mongoose.ws/ota/
 // Settable in mongoose_config.h
 #ifndef MG_OTA_URL
 #define MG_OTA_URL NULL
 #endif
 
+// PEM or DER CA certificate used to authenticate an HTTPS OTA server. Set to
+// NULL to use HTTP. Set in mongoose_config.h.
+#ifndef MG_OTA_TLS_CA
+#define MG_OTA_TLS_CA NULL
+#endif
+
 // OTA status callback function for mg_ota_poll()
 #ifndef MG_OTA_STATUS_FN
 #define MG_OTA_STATUS_FN NULL
@@ -4821,8 +4829,9 @@ void mg_ota_url_check(struct mg_mgr *mgr, const char *metadata_url,
 // E.g. on STM32, uses the 96-bit MCU UID converted to a hex string.
 void mg_ota_device_id(char *buf, size_t len);
 
-// Checks for a firmware update over HTTP. Called automatically by mg_mgr_poll()
-// when MG_OTA_URL is set in mongoose_config.h. Do not call directly.
+// Checks for a firmware update over HTTP or HTTPS. Called automatically by
+// mg_mgr_poll() when MG_OTA_URL is set in mongoose_config.h. Do not call
+// directly.
 void mg_ota_poll(struct mg_mgr *);
 
 
diff --git a/src/ota.c b/src/ota.c
index ff25f922..3f57adcc 100644
--- a/src/ota.c
+++ b/src/ota.c
@@ -3,6 +3,7 @@
 #include "json.h"
 #include "log.h"
 #include "printf.h"
+#include "tls.h"
 #include "url.h"
 #include "util.h"
 
@@ -26,6 +27,17 @@ static struct mg_ota_state {
 
 static void s_firmware_fn(struct mg_connection *c, int ev, void *ev_data);
 
+static bool s_tls_init(struct mg_connection *c, const char *url) {
+  struct mg_tls_opts opts = {
+      .ca = mg_str(MG_OTA_TLS_CA), .name = mg_url_host(url)};
+  if (opts.ca.len == 0) {
+    mg_error(c, "MG_OTA_TLS_CA is not configured");
+  } else {
+    mg_tls_init(c, &opts);
+  }
+  return c->is_tls_hs != 0 && !c->is_closing;
+}
+
 #if MG_ENABLE_CUSTOM_DEVICE_ID
 #else
 void mg_ota_device_id(char *buf, size_t len) {
@@ -58,6 +70,11 @@ void mg_ota_device_id(char *buf, size_t len) {
 
 static void s_version_fn(struct mg_connection *c, int ev, void *ev_data) {
   uint64_t expiration = *(uint64_t *) c->data;
+  if (s_ota == NULL) {
+    c->fn = NULL;
+    c->is_closing = 1;
+    return;
+  }
   if (ev == MG_EV_POLL) {
     if (mg_millis() > expiration) mg_error(c, "Metadata timeout");
   } else if (ev == MG_EV_CONNECT) {
@@ -65,6 +82,9 @@ static void s_version_fn(struct mg_connection *c, int ev, void *ev_data) {
     struct mg_str host = mg_url_host(s_ota->json_url);
     const char *uri = mg_url_uri(s_ota->json_url);
     const char *sep = strchr(uri, '?') == NULL ? "?" : "&";
+    if (mg_url_is_ssl(s_ota->json_url)) {
+      if (!s_tls_init(c, s_ota->json_url)) return;
+    }
     mg_ota_device_id(id, sizeof(id));
     id[sizeof(id) - 1] = '\0';
     mg_printf(
@@ -130,10 +150,18 @@ static void status_fn_2(struct mg_connection *c, const char *errmsg) {
 
 static void s_firmware_fn(struct mg_connection *c, int ev, void *ev_data) {
   uint64_t expiration = *(uint64_t *) c->data;
+  if (s_ota == NULL) {
+    c->fn = NULL;
+    c->is_closing = 1;
+    return;
+  }
   if (ev == MG_EV_POLL) {
     if (mg_millis() > expiration) mg_error(c, "OTA timeout");
   } else if (ev == MG_EV_CONNECT) {
     struct mg_str host = mg_url_host(s_ota->url);
+    if (mg_url_is_ssl(s_ota->url)) {
+      if (!s_tls_init(c, s_ota->url)) return;
+    }
     mg_printf(c,
               "GET %s HTTP/1.1\r\n"
               "Host: %.*s\r\n"
diff --git a/src/ota.h b/src/ota.h
index b99f9308..c8a861cd 100644
--- a/src/ota.h
+++ b/src/ota.h
@@ -2,7 +2,7 @@
 //
 // This is a low-level OTA API, not intended to be called directly by users.
 // Users are provided with a higher-level API:
-// - defining MG_OTA_URL enables HTTP pull-based updates
+// - defining MG_OTA_URL enables HTTP or HTTPS pull-based updates
 // - mg_http_start_ota() enables push-based updates
 //
 // However, it is possible to use the mg_ota_* API directly. Below is the
@@ -149,8 +149,10 @@ enum {
     }                                                              \
   } while (0)
 
-// Pull-based OTA over HTTP. Fetches metadata_url, which must return a JSON
-// object like: { "version": "1.2.3", "url": "FIRMWARE_URL", "size": 324645 }
+// Pull-based OTA over HTTP or HTTPS. If it's HTTPS, MG_OTA_TLS_CA
+// needs to be defined. Fetches metadata_url, which must
+// return a JSON object like:
+// { "version": "1.2.3", "url": "FIRMWARE_URL", "size": 324645 }
 // If the server version differs from MG_OTA_FIRMWARE_VERSION, downloads
 // FIRMWARE_URL and performs the OTA update. fn is called on every outcome:
 // NULL on successful flash, "Same version" when already up to date, or an
@@ -160,12 +162,18 @@ void mg_ota_url_check(struct mg_mgr *mgr, const char *metadata_url,
                       void (*fn)(const char *error_message));
 
 // Firmware info URL for mg_ota_poll() which calls mg_ota_url_check().
-// Example:  "http://mongoose.ws/ota/u/0/ota.json". See http://mongoose.ws/ota/
+// Example: "http://mongoose.ws/ota/u/0/ota.json". See http://mongoose.ws/ota/
 // Settable in mongoose_config.h
 #ifndef MG_OTA_URL
 #define MG_OTA_URL NULL
 #endif
 
+// PEM or DER CA certificate used to authenticate an HTTPS OTA server. Set to
+// NULL to use HTTP. Set in mongoose_config.h.
+#ifndef MG_OTA_TLS_CA
+#define MG_OTA_TLS_CA NULL
+#endif
+
 // OTA status callback function for mg_ota_poll()
 #ifndef MG_OTA_STATUS_FN
 #define MG_OTA_STATUS_FN NULL
@@ -195,6 +203,7 @@ void mg_ota_url_check(struct mg_mgr *mgr, const char *metadata_url,
 // E.g. on STM32, uses the 96-bit MCU UID converted to a hex string.
 void mg_ota_device_id(char *buf, size_t len);
 
-// Checks for a firmware update over HTTP. Called automatically by mg_mgr_poll()
-// when MG_OTA_URL is set in mongoose_config.h. Do not call directly.
+// Checks for a firmware update over HTTP or HTTPS. Called automatically by
+// mg_mgr_poll() when MG_OTA_URL is set in mongoose_config.h. Do not call
+// directly.
 void mg_ota_poll(struct mg_mgr *);