diff --git a/src/libopensc/card-openpgp.c b/src/libopensc/card-openpgp.c
index 956605ad..ab37bb5f 100644
--- a/src/libopensc/card-openpgp.c
+++ b/src/libopensc/card-openpgp.c
@@ -2265,6 +2265,7 @@ pgp_store_creationtime(sc_card_t *card, u8 key_id, time_t *outtime)
 	const size_t timestrlen = 64;
 	char timestring[65];
 	u8 buf[4];
+	struct tm tm;
 
 	LOG_FUNC_CALLED(card->ctx);
 
@@ -2278,7 +2279,14 @@ pgp_store_creationtime(sc_card_t *card, u8 key_id, time_t *outtime)
 		/* set output */
 		*outtime = createtime = time(NULL);
 
-	strftime(timestring, timestrlen, "%c %Z", gmtime(&createtime));
+#ifdef _WIN32
+	if (0 != gmtime_s(&tm, &createtime))
+		LOG_FUNC_RETURN(card->ctx, SC_ERROR_INTERNAL);
+#else
+	if (NULL == gmtime_r(&createtime, &tm))
+		LOG_FUNC_RETURN(card->ctx, SC_ERROR_INTERNAL);
+#endif
+	strftime(timestring, timestrlen, "%c %Z", &tm);
 	sc_log(card->ctx, "Creation time %s.", timestring);
 	/* Code borrowed from GnuPG */
 	ulong2bebytes(buf, (unsigned long)createtime);
diff --git a/src/libopensc/pkcs15.c b/src/libopensc/pkcs15.c
index 31e97cb1..8c4dc7ae 100644
--- a/src/libopensc/pkcs15.c
+++ b/src/libopensc/pkcs15.c
@@ -2605,7 +2605,7 @@ sc_pkcs15_get_generalized_time(struct sc_context *ctx, char **out)
 #ifdef HAVE_GETTIMEOFDAY
 	struct timeval tv;
 #endif
-	struct tm *tm_time;
+	struct tm tm;
 	time_t t;
 
 	if (!ctx || !out)
@@ -2618,16 +2618,21 @@ sc_pkcs15_get_generalized_time(struct sc_context *ctx, char **out)
 #else
 	t = time(NULL);
 #endif
-	tm_time = gmtime(&t);
-	if (!tm_time)
-		LOG_TEST_RET(ctx, SC_ERROR_INTERNAL, "gmtime failed");
+
+#ifdef _WIN32
+	if (0 != gmtime_s(&tm, &t))
+		LOG_FUNC_RETURN(ctx, SC_ERROR_INTERNAL);
+#else
+	if (NULL == gmtime_r(&t, &tm))
+		LOG_FUNC_RETURN(ctx, SC_ERROR_INTERNAL);
+#endif
 
 	*out = calloc(1, 16);
 	if (*out == NULL)
 		LOG_TEST_RET(ctx, SC_ERROR_OUT_OF_MEMORY, "memory failure");
 
 	/* print time in generalized time format */
-	if (!strftime(*out, 16, "%Y%m%d%H%M%SZ", tm_time)) {
+	if (!strftime(*out, 16, "%Y%m%d%H%M%SZ", &tm)) {
 		free(*out);
 		LOG_TEST_RET(ctx, SC_ERROR_INTERNAL, "strftime failed");
 	}
diff --git a/src/tools/openpgp-tool.c b/src/tools/openpgp-tool.c
index eb071c44..25174ee2 100644
--- a/src/tools/openpgp-tool.c
+++ b/src/tools/openpgp-tool.c
@@ -240,11 +240,17 @@ static char *prettify_date(u8 *data, size_t length)
 {
 	if (data != NULL && length == 4) {
 		time_t time = (time_t) (data[0] << 24 | data[1] << 16 | data[2] << 8 | data[3]);
-		struct tm *tp;
+		struct tm tm;
 		static char result[64];	/* large enough */
 
-		tp = gmtime(&time);
-		strftime(result, sizeof(result), "%Y-%m-%d %H:%M:%S", tp);
+#ifdef _WIN32
+		if (0 != gmtime_s(&tm, &time))
+			return NULL;
+#else
+		if (NULL == gmtime_r(&time, &tm))
+			return NULL;
+#endif
+		strftime(result, sizeof(result), "%Y-%m-%d %H:%M:%S", &tm);
 		return result;
 	}
 	return NULL;