diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index cc6636d..f3f3b07 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -8,7 +8,7 @@ jobs:
   test-bot:
     strategy:
       matrix:
-        os: [macos-latest]
+        os: [macos-10.15, macos-11.0]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Set up Homebrew
diff --git a/Formula/cvc4.rb b/Formula/cvc4.rb
index a269414..d776846 100644
--- a/Formula/cvc4.rb
+++ b/Formula/cvc4.rb
@@ -79,7 +79,7 @@ def install
     EOS
     result = shell_output "#{bin}/cvc4 #{testpath/"simple.cvc"}"
     assert_match(/entailed/, result)
-    (testpath/"simple.smt").write <<~EOS
+    (testpath/"simple.smt2").write <<~EOS
       (set-option :produce-models true)
       (set-logic QF_BV)
       (define-fun s_2 () Bool false)
@@ -87,7 +87,7 @@ def install
       (assert (not s_1))
       (check-sat)
     EOS
-    result = shell_output "#{bin}/cvc4 --lang smt #{testpath/"simple.smt"}"
+    result = shell_output "#{bin}/cvc4 --lang smt2 #{testpath/"simple.smt2"}"
     assert_match(/unsat/, result)
   end