diff --git a/cabal.project b/cabal.project
index 74d6d74c4c8e7165997b6a65734cc6d03234a490..55be17a13a683db9dd1f7743b243c5f56a0f587a 100644
--- a/cabal.project
+++ b/cabal.project
@@ -10,4 +10,4 @@ package zlib
         -- fixes build failures when the underlying zlib is not in the
         -- traditional location but is discoverable with pkg-config.  It might
         -- break non-pkg-config platforms.
-        -- flags: +pkg-config
+        flags: +pkg-config