diff --git a/acinclude.m4 b/acinclude.m4
index 45940732..84c10818 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -15,12 +15,12 @@ AC_DEFUN([COMPILER_FLAGS], [
 		CFLAGS="-Wall -O2 -D_FORTIFY_SOURCE=2"
 	fi
 	if (test "$USE_MAINTAINER_MODE" = "yes"); then
-		CFLAGS+=" -Werror -Wextra"
-		CFLAGS+=" -Wno-unused-parameter"
-		CFLAGS+=" -Wno-missing-field-initializers"
-		CFLAGS+=" -Wdeclaration-after-statement"
-		CFLAGS+=" -Wmissing-declarations"
-		CFLAGS+=" -Wredundant-decls"
-		CFLAGS+=" -Wcast-align"
+		CFLAGS="$CFLAGS -Werror -Wextra"
+		CFLAGS="$CFLAGS -Wno-unused-parameter"
+		CFLAGS="$CFLAGS -Wno-missing-field-initializers"
+		CFLAGS="$CFLAGS -Wdeclaration-after-statement"
+		CFLAGS="$CFLAGS -Wmissing-declarations"
+		CFLAGS="$CFLAGS -Wredundant-decls"
+		CFLAGS="$CFLAGS -Wcast-align"
 	fi
 ])