@@ -20,11 +20,14 @@
 CPP="$OBJCPP"
 CPPFLAGS="$CPPFLAGS $OBJCPPFLAGS"
 OBJCFLAGS="$OBJCFLAGS -Wall -fexceptions -fobjc-exceptions"
 OBJCFLAGS="$OBJCFLAGS -fconstant-string-class=OFConstantString"
 
-AX_CHECK_COMPILER_FLAGS(-std=gnu99, [OBJCFLAGS="$OBJCFLAGS -std=gnu99"])
+AX_CHECK_COMPILER_FLAGS(-std=gnu99, [
+	OBJCFLAGS="$OBJCFLAGS -std=gnu99"
+	AC_SUBST(GNU99, "-std=gnu99")
+])
 AX_CHECK_COMPILER_FLAGS(-fgnu89-inline, [OBJCFLAGS="$OBJCFLAGS -fgnu89-inline"])
 AX_CHECK_COMPILER_FLAGS(-pipe, [OBJCFLAGS="$OBJCFLAGS -pipe"])
 AX_CHECK_COMPILER_FLAGS(-fno-common, [OBJCFLAGS="$OBJCFLAGS -fno-common"])
 AX_CHECK_COMPILER_FLAGS(-fno-constant-cfstrings, [
 	OBJCFLAGS="$OBJCFLAGS -fno-constant-cfstrings"