diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c
index ee1ae1ab19..5012890ef3 100644
--- a/libavformat/wtvdec.c
+++ b/libavformat/wtvdec.c
@@ -389,7 +389,7 @@ static int filetime_to_iso8601(char *buf, int buf_size, int64_t value)
     struct tm *tm = gmtime(&t);
     if (!tm)
         return -1;
-    strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", gmtime(&t));
+    strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
     return 0;
 }
 
@@ -403,7 +403,7 @@ static int crazytime_to_iso8601(char *buf, int buf_size, int64_t value)
     struct tm *tm = gmtime(&t);
     if (!tm)
         return -1;
-    strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", gmtime(&t));
+    strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
     return 0;
 }
 
@@ -414,10 +414,10 @@ static int crazytime_to_iso8601(char *buf, int buf_size, int64_t value)
 static int oledate_to_iso8601(char *buf, int buf_size, int64_t value)
 {
     time_t t = (av_int2double(value) - 25569.0) * 86400;
-    struct tm *result= gmtime(&t);
-    if (!result)
+    struct tm *tm= gmtime(&t);
+    if (!tm)
         return -1;
-    strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", result);
+    strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
     return 0;
 }