diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 840e325..0eedc72 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -29,5 +29,11 @@ jobs:
       if: matrix.go-version == '1.16' && matrix.platform == 'ubuntu-latest'
       run: diff -u <(echo -n) <(go fmt $(go list ./...))
 
+    - name: Check Go modules
+      if: matrix.go-version == '1.16'
+      run: |
+        go mod tidy
+        git diff --exit-code
+
     - name: Run unit tests
       run: go test -v ./...
diff --git a/go.sum b/go.sum
index 977a1fe..df556d9 100644
--- a/go.sum
+++ b/go.sum
@@ -1,6 +1,2 @@
-golang.org/x/sys v0.0.0-20210216163648-f7da38b97c65 h1:pTMjDVnP5eVRRlWO76rEWJ8JoC6Lf1CmyjPZXRiy2Sw=
-golang.org/x/sys v0.0.0-20210216163648-f7da38b97c65/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210216224549-f992740a1bac h1:9glrpwtNjBYgRpb67AZJKHfzj1stG/8BL5H7In2oTC4=
-golang.org/x/sys v0.0.0-20210216224549-f992740a1bac/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210301091718-77cc2087c03b h1:kHlr0tATeLRMEiZJu5CknOw/E8V6h69sXXQFGoPtjcc=
 golang.org/x/sys v0.0.0-20210301091718-77cc2087c03b/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=