diff --git a/pkgs/development/interpreters/php/default.nix b/pkgs/development/interpreters/php/default.nix
index 1acd5c4a5224..2c5546482907 100644
--- a/pkgs/development/interpreters/php/default.nix
+++ b/pkgs/development/interpreters/php/default.nix
@@ -21,6 +21,8 @@ let
 
       buildInputs = [ flex bison pkgconfig ];
 
+      configureFlags = ["EXTENSION_DIR=$(out)/lib/php/extensions"];
+
       flags = {
 
         # much left to do here...