diff --git a/windows12.cabal b/windows12.cabal
index 6eaf50f..2ee9a6b 100644
--- a/windows12.cabal
+++ b/windows12.cabal
@@ -69,7 +69,10 @@ executable windows12
     -- other-extensions:
 
     -- Other library packages from which modules are imported.
-    build-depends:    base ^>=4.18.2.1
+    build-depends:
+        base >= 4.15.1 && < 4.16,
+        llvm-hs-pure >= 9.0.0 && < 9.1,
+
 
     -- Directories containing source files.
     hs-source-dirs:   src