diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1af921e..852eee0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        nim: [1.2.16, 1.4.8, stable]
+        nim: [1.2.16, stable]
     steps:
     - name: Checkout
       uses: actions/checkout@v2
diff --git a/testmodule/testContracts.nim b/testmodule/testContracts.nim
index f0a2169..842c116 100644
--- a/testmodule/testContracts.nim
+++ b/testmodule/testContracts.nim
@@ -74,9 +74,7 @@ suite "Contracts":
               holder: Address,
               amount: UInt256): ?TransactionResponse {.contract.}
     let txResp = await token.mint(accounts[1], 100.u256)
-    # `of` instead of `is` due to v1.4.8 compiler error:
-    # "invalid type: 'type Confirmable' for var"
-    check txResp of (?TransactionResponse)
+    check txResp is (?TransactionResponse)
     check txResp.isSome
 
   test "can call non-constant functions with a Confirmable return type":