diff --git a/media/libpng/moz.build b/media/libpng/moz.build
index e470c5398475bedba0a446f48915fd98016e81a2..9ea7d8d44837867844d3df37e45495b0491cbfc6 100644
--- a/media/libpng/moz.build
+++ b/media/libpng/moz.build
@@ -64,3 +64,6 @@ FINAL_LIBRARY = 'gkmedias'
 
 # We allow warnings for third-party code that can be updated from upstream.
 ALLOW_COMPILER_WARNINGS = True
+
+if CONFIG['GNU_CC']:
+    CFLAGS += ['-std=c89']
diff --git a/mozilla-config.h.in b/mozilla-config.h.in
index 7484180b0db64102d0a1883a50e33148cda2f1f6..6883a7be2587203836d1548fb92e4fa69f47310e 100644
--- a/mozilla-config.h.in
+++ b/mozilla-config.h.in
@@ -13,7 +13,7 @@
 #endif
 #endif
 
-// Expands to all the defines from configure.
+/* Expands to all the defines from configure. */
 #undef ALLDEFINES
 
 /*