diff --git a/pkgs/development/interpreters/php/generic.nix b/pkgs/development/interpreters/php/generic.nix
index d86ea48afe1a..558fa45a1fd9 100644
--- a/pkgs/development/interpreters/php/generic.nix
+++ b/pkgs/development/interpreters/php/generic.nix
@@ -124,15 +124,15 @@ let
                 ln -s ${extraInit} $out/lib/php.ini
 
                 if test -e $out/bin/php; then
-                  wrapProgram $out/bin/php --prefix PHP_INI_SCAN_DIR : $out/lib
+                  wrapProgram $out/bin/php --set PHP_INI_SCAN_DIR $out/lib
                 fi
 
                 if test -e $out/bin/php-fpm; then
-                  wrapProgram $out/bin/php-fpm --prefix PHP_INI_SCAN_DIR : $out/lib
+                  wrapProgram $out/bin/php-fpm --set PHP_INI_SCAN_DIR $out/lib
                 fi
 
                 if test -e $out/bin/phpdbg; then
-                  wrapProgram $out/bin/phpdbg --prefix PHP_INI_SCAN_DIR : $out/lib
+                  wrapProgram $out/bin/phpdbg --set PHP_INI_SCAN_DIR $out/lib
                 fi
               '';
             };