diff --git a/src/h2.c b/src/h2.c
index 09ee2480..9560ab07 100644
--- a/src/h2.c
+++ b/src/h2.c
@@ -1963,7 +1963,7 @@ h2_send_headers (request_st * const r, connection * const con)
 
     if (!light_btst(r->resp_htags, HTTP_HEADER_DATE)) {
         /* HTTP/1.1 and later requires a Date: header */
-        /* "date: " 6-chars + 30-chars for "%a, %d %b %Y %H:%M:%S GMT" + '\0' */
+        /* "date: " 6-chars + 30-chars for "%a, %d %b %Y %T GMT" + '\0' */
         static time_t tlast = 0;
         static char tstr[36] = "date: ";
 
diff --git a/src/http-header-glue.c b/src/http-header-glue.c
index 64c68c6c..7d9afcd2 100644
--- a/src/http-header-glue.c
+++ b/src/http-header-glue.c
@@ -140,7 +140,7 @@ struct mtime_cache_type {
 };
 static struct mtime_cache_type mtime_cache[MTIME_CACHE_MAX];
 static char mtime_cache_str[MTIME_CACHE_MAX][30];
-/* 30-chars for "%a, %d %b %Y %H:%M:%S GMT" */
+/* 30-chars for "%a, %d %b %Y %T GMT" */
 
 void strftime_cache_reset(void) {
     for (int i = 0; i < MTIME_CACHE_MAX; ++i) {
diff --git a/src/log.c b/src/log.c
index 94b18afb..fc1f9d12 100644
--- a/src/log.c
+++ b/src/log.c
@@ -70,7 +70,7 @@ ssize_t write_all(int fd, const void * const buf, size_t count) {
 static int log_buffer_prepare(const log_error_st *errh, const char *filename, unsigned int line, buffer *b) {
 	static time_t tlast;
 	static uint32_t tlen;
-	static char tstr[24]; /* 20 "%Y-%m-%d %H:%M:%S" incl '\0' +3 ": (" */
+	static char tstr[24]; /* 20 "%F %T" incl '\0' +3 ": (" */
 	switch(errh->errorlog_mode) {
 	case ERRORLOG_PIPE:
 	case ERRORLOG_FILE:
@@ -81,7 +81,7 @@ static int log_buffer_prepare(const log_error_st *errh, const char *filename, un
 			struct tm tm;
 			tlast = log_epoch_secs;
 			tlen = (uint32_t)
-			  strftime(tstr, sizeof(tstr), "%Y-%m-%d %H:%M:%S",
+			  strftime(tstr, sizeof(tstr), "%F %T",
 			           localtime_r(&tlast, &tm));
 			tstr[  tlen] = ':';
 			tstr[++tlen] = ' ';
diff --git a/src/mod_accesslog.c b/src/mod_accesslog.c
index 10b1a0b1..20407a97 100644
--- a/src/mod_accesslog.c
+++ b/src/mod_accesslog.c
@@ -891,11 +891,11 @@ static int log_access_record (const request_st * const r, buffer * const b, form
 					buffer_clear(ts_accesslog_str);
 				      #if defined(HAVE_STRUCT_TM_GMTOFF)
 					buffer_append_strftime(ts_accesslog_str,
-					                       fmt ? fmt : "[%d/%b/%Y:%H:%M:%S %z]",
+					                       fmt ? fmt : "[%d/%b/%Y:%T %z]",
 					                       localtime_r(&t, &tm));
 				      #else /* HAVE_STRUCT_TM_GMTOFF */
 					buffer_append_strftime(ts_accesslog_str,
-					                       fmt ? fmt : "[%d/%b/%Y:%H:%M:%S +0000]",
+					                       fmt ? fmt : "[%d/%b/%Y:%T +0000]",
 					                       gmtime_r(&t, &tm));
 				      #endif /* HAVE_STRUCT_TM_GMTOFF */
 					buffer_append_string_buffer(b, ts_accesslog_str);
diff --git a/src/mod_dirlisting.c b/src/mod_dirlisting.c
index a7b69635..ed3e2f36 100644
--- a/src/mod_dirlisting.c
+++ b/src/mod_dirlisting.c
@@ -961,7 +961,7 @@ static int http_list_directory(request_st * const r, plugin_data * const p) {
 		buffer_append_string_len(out, CONST_STR_LEN("/\">"));
 		buffer_append_string_encoded(out, DIRLIST_ENT_NAME(tmp), tmp->namelen, ENCODING_MINIMAL_XML);
 		buffer_append_string_len(out, CONST_STR_LEN("</a>/</td><td class=\"m\">"));
-		buffer_append_strftime(out, "%Y-%b-%d %H:%M:%S", localtime_r(&tmp->mtime, &tm));
+		buffer_append_strftime(out, "%Y-%b-%d %T", localtime_r(&tmp->mtime, &tm));
 		buffer_append_string_len(out, CONST_STR_LEN("</td><td class=\"s\">- &nbsp;</td><td class=\"t\">Directory</td></tr>\n"));
 
 		free(tmp);
@@ -1005,7 +1005,7 @@ static int http_list_directory(request_st * const r, plugin_data * const p) {
 		buffer_append_string_len(out, CONST_STR_LEN("\">"));
 		buffer_append_string_encoded(out, DIRLIST_ENT_NAME(tmp), tmp->namelen, ENCODING_MINIMAL_XML);
 		buffer_append_string_len(out, CONST_STR_LEN("</a></td><td class=\"m\">"));
-		buffer_append_strftime(out, "%Y-%b-%d %H:%M:%S", localtime_r(&tmp->mtime, &tm));
+		buffer_append_strftime(out, "%Y-%b-%d %T", localtime_r(&tmp->mtime, &tm));
 		buffer_append_string_len(out, CONST_STR_LEN("</td><td class=\"s\">"));
 		buffer_append_string(out, sizebuf);
 		buffer_append_string_len(out, CONST_STR_LEN("</td><td class=\"t\">"));
diff --git a/src/mod_expire.c b/src/mod_expire.c
index eefa3c1d..a2f42eb8 100644
--- a/src/mod_expire.c
+++ b/src/mod_expire.c
@@ -318,7 +318,7 @@ REQUEST_FUNC(mod_expire_handler) {
 	/* HTTP/1.0 */
 	vb = http_header_response_set_ptr(r, HTTP_HEADER_EXPIRES,
 	                                  CONST_STR_LEN("Expires"));
-	buffer_append_strftime(vb, "%a, %d %b %Y %H:%M:%S GMT", gmtime_r(&expires,&tm));
+	buffer_append_strftime(vb, "%a, %d %b %Y %T GMT", gmtime_r(&expires,&tm));
 
 	/* HTTP/1.1 */
 	vb = http_header_response_set_ptr(r, HTTP_HEADER_CACHE_CONTROL,
diff --git a/src/mod_ssi.c b/src/mod_ssi.c
index fe18242e..779fa22b 100644
--- a/src/mod_ssi.c
+++ b/src/mod_ssi.c
@@ -185,7 +185,7 @@ static int build_ssi_cgi_vars(request_st * const r, handler_ctx * const p) {
 
 static const char * mod_ssi_timefmt (handler_ctx * const hctx) {
     return buffer_string_is_empty(hctx->timefmt)
-      ? "%a, %d %b %Y %H:%M:%S %Z"
+      ? "%a, %d %b %Y %T %Z"
       : hctx->timefmt->ptr;
 }
 
diff --git a/src/mod_status.c b/src/mod_status.c
index 787a1ae2..6ca40ce2 100644
--- a/src/mod_status.c
+++ b/src/mod_status.c
@@ -475,7 +475,7 @@ static handler_t mod_status_handle_server_status_html(server *srv, request_st *
 	ts = srv->startup_ts;
 
 	struct tm tm;
-	buffer_append_strftime(b, "%Y-%m-%d %H:%M:%S", localtime_r(&ts, &tm));
+	buffer_append_strftime(b, "%F %T", localtime_r(&ts, &tm));
 	buffer_append_string_len(b, CONST_STR_LEN("</td></tr>\n"));
 
 
diff --git a/src/mod_webdav.c b/src/mod_webdav.c
index 0378e94e..a5b6b6a8 100644
--- a/src/mod_webdav.c
+++ b/src/mod_webdav.c
@@ -3081,7 +3081,7 @@ webdav_propfind_live_props (const webdav_propfind_bufs * const restrict pb,
         if (__builtin_expect( (NULL != gmtime_r(&pb->st.st_ctime, &tm)), 1)) {
             buffer_append_string_len(b, CONST_STR_LEN(
               "<D:creationdate ns0:dt=\"dateTime.tz\">"));
-            buffer_append_strftime(b, "%Y-%m-%dT%TZ", &tm));
+            buffer_append_strftime(b, "%FT%TZ", &tm));
             buffer_append_string_len(b, CONST_STR_LEN(
               "</D:creationdate>"));
         }
@@ -3177,7 +3177,7 @@ webdav_propfind_live_props (const webdav_propfind_bufs * const restrict pb,
         if (__builtin_expect( (NULL != gmtime_r(&pb->st.st_mtime, &tm)), 1)) {
             buffer_append_string_len(b, CONST_STR_LEN(
               "<D:getlastmodified ns0:dt=\"dateTime.rfc1123\">"));
-            buffer_append_strftime(b, "%a, %d %b %Y %H:%M:%S GMT", &tm);
+            buffer_append_strftime(b, "%a, %d %b %Y %T GMT", &tm);
             buffer_append_string_len(b, CONST_STR_LEN(
               "</D:getlastmodified>"));
         }
diff --git a/src/response.c b/src/response.c
index e486d6ee..c20834fe 100644
--- a/src/response.c
+++ b/src/response.c
@@ -136,7 +136,7 @@ http_response_write_header (request_st * const r)
 
 	if (!light_btst(r->resp_htags, HTTP_HEADER_DATE)) {
 		/* HTTP/1.1 and later requires a Date: header */
-		/* "\r\nDate: " 8-chars + 30-chars "%a, %d %b %Y %H:%M:%S GMT" + '\0' */
+		/* "\r\nDate: " 8-chars + 30-chars "%a, %d %b %Y %T GMT" + '\0' */
 		static time_t tlast = 0;
 		static char tstr[40] = "\r\nDate: ";