diff --git a/winsup/ChangeLog b/winsup/ChangeLog
index 09a3436b1..9bebbe46c 100644
--- a/winsup/ChangeLog
+++ b/winsup/ChangeLog
@@ -1,3 +1,8 @@
+2012-07-06  Corinna Vinschen  <corinna@vinschen.de>
+
+	* Makefile.common (ALL_CFLAGS): Change := to = to allow overriding in
+	dependent Makefiles.
+
 2012-01-09  Corinna Vinschen  <corinna@vinschen.de>
 
 	* Makefile.common (MINGW_LDFLAGS): Correctly use -L rather than -B here.
diff --git a/winsup/Makefile.common b/winsup/Makefile.common
index d496fb8d6..569b2a3fc 100644
--- a/winsup/Makefile.common
+++ b/winsup/Makefile.common
@@ -113,7 +113,7 @@ LIBC:=$(newlib_build)/libc/libc.a
 LIBM:=$(newlib_build)/libm/libm.a
 CRT0:=$(cygwin_build)/crt0.o
 
-ALL_CFLAGS:=$(DEFS) $(MALLOC_DEBUG) $(CFLAGS) $(GCC_DEFAULT_OPTIONS)
+ALL_CFLAGS=$(DEFS) $(MALLOC_DEBUG) $(CFLAGS) $(GCC_DEFAULT_OPTIONS)
 ALL_CXXFLAGS=$(DEFS) $(MALLOC_DEBUG) $(CXXFLAGS) $(GCC_DEFAULT_OPTIONS)
 
 ifndef PREPROCESS