diff --git a/build/php.m4 b/build/php.m4
index 185606adea9..d06375c94f3 100644
--- a/build/php.m4
+++ b/build/php.m4
@@ -1740,7 +1740,7 @@ AC_DEFUN([PHP_PROG_RE2C],[
   esac
 
   PHP_SUBST([RE2C])
-  AS_VAR_SET([RE2C_FLAGS], [m4_normalize([$2])])
+  AS_VAR_SET([RE2C_FLAGS], [m4_normalize(["$2"])])
   PHP_SUBST([RE2C_FLAGS])
 ])