diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index d39d6ca..96fbc60 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -240,7 +240,7 @@ endif # not PGXS
 CC = @CC@
 GCC = @GCC@
 SUN_STUDIO_CC = @SUN_STUDIO_CC@
-CFLAGS = @CFLAGS@
+CFLAGS = @CFLAGS@ -Werror
 CFLAGS_VECTOR = @CFLAGS_VECTOR@
 CFLAGS_SSE42 = @CFLAGS_SSE42@