diff --git a/GNUmakefile b/GNUmakefile
index a485bcd..9dd381f 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -74,7 +74,7 @@ libobjc_CPPFLAGS += -D__OBJC_RUNTIME_INTERNAL__=1 -D_XOPEN_SOURCE=500
 # Note to Riccardo.  Please do not 'fix' C99isms in this.  The new ABI is only
 # useful on compilers that support C99 (currently only clang), so there is no
 # benefit from supporting platforms with no C99 compiler.
-libobjc_CFLAGS += -std=c99 -g -fexceptions #-fvisibility=hidden
+libobjc_CFLAGS += -std=gnu99 -g -fexceptions #-fvisibility=hidden
 # Uncomment this when debugging - it makes everything slow, but means that the
 # debugger actually works...
 #libobjc_CFLAGS += -fno-inline