diff --git a/sapi/apache2handler/config.m4 b/sapi/apache2handler/config.m4
index 3cf76adea3b2e..3785bd2bcd261 100644
--- a/sapi/apache2handler/config.m4
+++ b/sapi/apache2handler/config.m4
@@ -77,7 +77,7 @@ if test "$PHP_APXS2" != "no"; then
   fi
 
   LIBPHP_CFLAGS="-shared"
-  PHP_SUBST(LIBPHP_CFLAGS)
+  PHP_SUBST([LIBPHP_CFLAGS])
 
   case $host_alias in
   *aix*)
@@ -96,7 +96,7 @@ if test "$PHP_APXS2" != "no"; then
         MH_BUNDLE_FLAGS="`$APU_CONFIG --ldflags --link-ld --libs` $MH_BUNDLE_FLAGS"
     fi
     MH_BUNDLE_FLAGS="-bundle -bundle_loader $APXS_HTTPD $MH_BUNDLE_FLAGS"
-    PHP_SUBST(MH_BUNDLE_FLAGS)
+    PHP_SUBST([MH_BUNDLE_FLAGS])
     PHP_SELECT_SAPI(apache2handler, bundle, mod_php.c sapi_apache2.c apache_config.c php_functions.c, $APACHE_CFLAGS)
     SAPI_SHARED=libs/libphp.so
     INSTALL_IT="$INSTALL_IT $SAPI_SHARED"
@@ -119,7 +119,6 @@ if test "$PHP_APXS2" != "no"; then
     fi
   fi
   AC_MSG_RESULT(yes)
-  PHP_SUBST(APXS)
 else
   AC_MSG_RESULT(no)
 fi
diff --git a/sapi/cgi/config9.m4 b/sapi/cgi/config9.m4
index 43ff00ecb7954..ccc4d0b79c062 100644
--- a/sapi/cgi/config9.m4
+++ b/sapi/cgi/config9.m4
@@ -55,9 +55,8 @@ if test "$PHP_CGI" != "no"; then
       ;;
     esac
 
-    dnl Expose to Makefile.
-    PHP_SUBST(SAPI_CGI_PATH)
-    PHP_SUBST(BUILD_CGI)
+    PHP_SUBST([SAPI_CGI_PATH])
+    PHP_SUBST([BUILD_CGI])
 
     PHP_OUTPUT(sapi/cgi/php-cgi.1)
 else
diff --git a/sapi/cli/config.m4 b/sapi/cli/config.m4
index b6a708c0e9682..c8d7684164c36 100644
--- a/sapi/cli/config.m4
+++ b/sapi/cli/config.m4
@@ -48,11 +48,10 @@ if test "$PHP_CLI" != "no"; then
 
   dnl Set executable for tests.
   PHP_EXECUTABLE="\$(top_builddir)/\$(SAPI_CLI_PATH)"
-  PHP_SUBST(PHP_EXECUTABLE)
 
-  dnl Expose to Makefile.
-  PHP_SUBST(SAPI_CLI_PATH)
-  PHP_SUBST(BUILD_CLI)
+  PHP_SUBST([PHP_EXECUTABLE])
+  PHP_SUBST([SAPI_CLI_PATH])
+  PHP_SUBST([BUILD_CLI])
 
   PHP_OUTPUT(sapi/cli/php.1)
 
diff --git a/sapi/embed/config.m4 b/sapi/embed/config.m4
index f9838f1d08c11..3cc1e55170250 100644
--- a/sapi/embed/config.m4
+++ b/sapi/embed/config.m4
@@ -24,7 +24,7 @@ if test "$PHP_EMBED" != "no"; then
       ;;
   esac
   if test "$PHP_EMBED_TYPE" != "no"; then
-    PHP_SUBST(LIBPHP_CFLAGS)
+    PHP_SUBST([LIBPHP_CFLAGS])
     PHP_SELECT_SAPI(embed, $PHP_EMBED_TYPE, php_embed.c, -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1)
     PHP_INSTALL_HEADERS([sapi/embed], [php_embed.h])
   fi
diff --git a/sapi/fpm/config.m4 b/sapi/fpm/config.m4
index 0c78cbcff97e5..694241b43aa7a 100644
--- a/sapi/fpm/config.m4
+++ b/sapi/fpm/config.m4
@@ -633,8 +633,8 @@ if test "$PHP_FPM" != "no"; then
       ;;
   esac
 
-  PHP_SUBST(SAPI_FPM_PATH)
-  PHP_SUBST(BUILD_FPM)
+  PHP_SUBST([SAPI_FPM_PATH])
+  PHP_SUBST([BUILD_FPM])
 
 else
   AC_MSG_RESULT(no)
diff --git a/sapi/fuzzer/config.m4 b/sapi/fuzzer/config.m4
index 10a623ff82e10..c4d6d662e0037 100644
--- a/sapi/fuzzer/config.m4
+++ b/sapi/fuzzer/config.m4
@@ -13,7 +13,7 @@ dnl PHP_FUZZER_TARGET(name, target-var)
 dnl
 AC_DEFUN([PHP_FUZZER_TARGET], [
   PHP_FUZZER_BINARIES="$PHP_FUZZER_BINARIES $SAPI_FUZZER_PATH/php-fuzz-$1"
-  PHP_SUBST($2)
+  PHP_SUBST([$2])
   PHP_ADD_SOURCES_X([sapi/fuzzer],[fuzzer-$1.c],[],$2)
   $2="[$]$2 $FUZZER_COMMON_OBJS"
 ])
@@ -29,7 +29,7 @@ if test "$PHP_FUZZER" != "no"; then
   AC_PROG_CXXCPP
   PHP_ADD_MAKEFILE_FRAGMENT($abs_srcdir/sapi/fuzzer/Makefile.frag)
   SAPI_FUZZER_PATH=sapi/fuzzer
-  PHP_SUBST(SAPI_FUZZER_PATH)
+  PHP_SUBST([SAPI_FUZZER_PATH])
   if test -z "$LIB_FUZZING_ENGINE"; then
     FUZZING_LIB="-fsanitize=fuzzer"
     FUZZING_CC="$CC"
@@ -43,8 +43,8 @@ if test "$PHP_FUZZER" != "no"; then
     FUZZING_LIB="$LIB_FUZZING_ENGINE"
     FUZZING_CC="$CXX -stdlib=libc++"
   fi
-  PHP_SUBST(FUZZING_LIB)
-  PHP_SUBST(FUZZING_CC)
+  PHP_SUBST([FUZZING_LIB])
+  PHP_SUBST([FUZZING_CC])
 
   dnl PHP_SELECT_SAPI(fuzzer-parser, program, $FUZZER_SOURCES, , '$(SAPI_FUZZER_PATH)')
 
@@ -73,5 +73,5 @@ if test "$PHP_FUZZER" != "no"; then
     fi
   fi
 
-  PHP_SUBST(PHP_FUZZER_BINARIES)
+  PHP_SUBST([PHP_FUZZER_BINARIES])
 fi
diff --git a/sapi/litespeed/config.m4 b/sapi/litespeed/config.m4
index f18697203cb2f..8fa434198019a 100644
--- a/sapi/litespeed/config.m4
+++ b/sapi/litespeed/config.m4
@@ -22,8 +22,8 @@ if test "$PHP_LITESPEED" != "no"; then
     ;;
   esac
 
-  PHP_SUBST(SAPI_LITESPEED_PATH)
-  PHP_SUBST(BUILD_LITESPEED)
+  PHP_SUBST([SAPI_LITESPEED_PATH])
+  PHP_SUBST([BUILD_LITESPEED])
 fi
 
 AC_MSG_RESULT($PHP_LITESPEED)
diff --git a/sapi/phpdbg/config.m4 b/sapi/phpdbg/config.m4
index eb32afe13f336..0039a736f29ab 100644
--- a/sapi/phpdbg/config.m4
+++ b/sapi/phpdbg/config.m4
@@ -67,8 +67,6 @@ if test "$PHP_PHPDBG" != "no"; then
     fi
   ],,[#include <linux/userfaultfd.h>])
 
-  PHP_SUBST(PHPDBG_EXTRA_LIBS)
-
   PHP_ADD_MAKEFILE_FRAGMENT([$abs_srcdir/sapi/phpdbg/Makefile.frag], [$abs_srcdir/sapi/phpdbg], [$abs_builddir/sapi/phpdbg])
   PHP_SELECT_SAPI(phpdbg, program, $PHP_PHPDBG_FILES, $PHP_PHPDBG_CFLAGS, [$(SAPI_PHPDBG_PATH)])
 
@@ -97,10 +95,11 @@ if test "$PHP_PHPDBG" != "no"; then
                 \-DPHPDBG_SHARED \
          -o \$(BUILD_SHARED)"
 
-  PHP_SUBST(BUILD_BINARY)
-  PHP_SUBST(BUILD_SHARED)
-  PHP_SUBST(BUILD_PHPDBG)
-  PHP_SUBST(BUILD_PHPDBG_SHARED)
+  PHP_SUBST([PHPDBG_EXTRA_LIBS])
+  PHP_SUBST([BUILD_BINARY])
+  PHP_SUBST([BUILD_SHARED])
+  PHP_SUBST([BUILD_PHPDBG])
+  PHP_SUBST([BUILD_PHPDBG_SHARED])
 
   PHP_OUTPUT(sapi/phpdbg/phpdbg.1)
 fi