diff --git a/build/php.m4 b/build/php.m4
index 47cb64eae60e..fde5ffbaeb1d 100644
--- a/build/php.m4
+++ b/build/php.m4
@@ -96,9 +96,8 @@ dnl
 dnl Adds "file" to the list of files generated by AC_OUTPUT. This macro can be
 dnl used several times.
 dnl
-AC_DEFUN([PHP_OUTPUT],[
-  PHP_OUTPUT_FILES="$PHP_OUTPUT_FILES $1"
-])
+AC_DEFUN([PHP_OUTPUT],
+[AS_VAR_APPEND([PHP_OUTPUT_FILES], [" m4_normalize([$1])"])])
 
 dnl ----------------------------------------------------------------------------
 dnl Build system base macros.
diff --git a/sapi/fpm/config.m4 b/sapi/fpm/config.m4
index baab47a60435..b8610367ccc2 100644
--- a/sapi/fpm/config.m4
+++ b/sapi/fpm/config.m4
@@ -508,7 +508,14 @@ if test "$PHP_FPM" != "no"; then
 
   PHP_ADD_BUILD_DIR([sapi/fpm/fpm])
   PHP_ADD_BUILD_DIR([sapi/fpm/fpm/events])
-  PHP_OUTPUT([sapi/fpm/php-fpm.conf sapi/fpm/www.conf sapi/fpm/init.d.php-fpm sapi/fpm/php-fpm.service sapi/fpm/php-fpm.8 sapi/fpm/status.html])
+  PHP_OUTPUT([
+    sapi/fpm/init.d.php-fpm
+    sapi/fpm/php-fpm.8
+    sapi/fpm/php-fpm.conf
+    sapi/fpm/php-fpm.service
+    sapi/fpm/status.html
+    sapi/fpm/www.conf
+  ])
   PHP_ADD_MAKEFILE_FRAGMENT([$abs_srcdir/sapi/fpm/Makefile.frag])
 
   SAPI_FPM_PATH=sapi/fpm/php-fpm