diff --git a/pkgs/development/php-packages/smbclient/default.nix b/pkgs/development/php-packages/smbclient/default.nix
index 689cc94b61c8..7b24722ec623 100644
--- a/pkgs/development/php-packages/smbclient/default.nix
+++ b/pkgs/development/php-packages/smbclient/default.nix
@@ -10,7 +10,7 @@ buildPecl {
   sha256 = "sha256-Hmp0RWOqxwCBXlca2YsRNahOhA1E5qxnmXSUx4Cpzec=";
 
   # TODO: remove this when upstream merges a fix - https://github.com/eduardok/libsmbclient-php/pull/66
-  LIBSMBCLIENT_INCDIR = "${samba.dev}/include/samba-4.0";
+  env.LIBSMBCLIENT_INCDIR = "${samba.dev}/include/samba-4.0";
 
   nativeBuildInputs = [ pkg-config ];
   buildInputs = [ samba ];