diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f681fb8..c658627 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -131,7 +131,7 @@ jobs:
         status=0
         for proof in *_proofs.tla; do
           echo "::group::Verifying $proof"
-          tlapm --cleanfp "$proof" || status=1
+          tlapm --strict --cleanfp "$proof" || status=1
           echo "::endgroup::"
         done
         exit $status
diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index b3d0a7a..48d70a2 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -55,7 +55,7 @@ jobs:
         status=0
         for proof in *_proofs.tla; do
           echo "::group::Verifying $proof"
-          tlapm --cleanfp "$proof" || status=1
+          tlapm --strict --cleanfp "$proof" || status=1
           echo "::endgroup::"
         done
         exit $status