diff --git a/pigz.c b/pigz.c
index c82c1eb..a771125 100644
--- a/pigz.c
+++ b/pigz.c
@@ -3922,8 +3922,8 @@
         vstrcpy(&g.inf, &g.inz, 0, "<stdin>");
         g.ind = 0;
         g.name = NULL;
-        g.mtime = g.headis & 2 ?
-                  (fstat(g.ind, &st) ? time(NULL) : st.st_mtime) : 0;
+        g.mtime = (g.headis & 2) && fstat(g.ind, &st) == 0 &&
+                  S_ISREG(st.st_mode) ? st.st_mtime : 0;
         len = 0;
     }
     else {