diff --git a/pkgs/development/interpreters/php/generic.nix b/pkgs/development/interpreters/php/generic.nix
index 191d589aa90..7812aaa1aec 100644
--- a/pkgs/development/interpreters/php/generic.nix
+++ b/pkgs/development/interpreters/php/generic.nix
@@ -189,7 +189,7 @@ let
               "--with-libxml-dir=${libxml2.dev}"
             ]
             ++ lib.optional pharSupport   "--enable-phar"
-            ++ lib.optional phpdbgSupport "--enable-phpdbg"
+            ++ lib.optional (!phpdbgSupport) "--disable-phpdbg"
 
 
             # Misc flags