diff --git a/package.yaml b/package.yaml
index ef7341e..b0f4572 100644
--- a/package.yaml
+++ b/package.yaml
@@ -27,7 +27,7 @@ library:
   - array                >= 0.5
   - text                 >= 1.1
   - bytestring           >= 0.10
-  - mtl                  >= 2.2
+  - mtl                  >= 2.2.1
   - transformers         >= 0.4
   - containers           >= 0.5
   - utf8-string          >= 1.0
@@ -47,6 +47,6 @@ tests:
     - directory          >= 1.3
     - text               >= 1.1
     - bytestring         >= 0.10
-    - mtl                == 2.2.1
+    - mtl                >= 2.2.1
     - tasty              >= 0.7
     - tasty-hunit        >= 0.4.1