diff --git a/.github/workflows/bors.yml b/.github/workflows/bors.yml
index 8fc6d556a045f..8ff4874f54a80 100644
--- a/.github/workflows/bors.yml
+++ b/.github/workflows/bors.yml
@@ -242,7 +242,11 @@ jobs:
 
       - name: test mathlib
         id: test
-        run: make -j 8 test
+        run: |
+          # Tests use parts of ProofWidgets not imported by Mathlib.
+          # Ensure everything has been built.
+          lake build ProofWidgets
+          make -j 8 test
 
       - name: lint mathlib
         id: lint
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 880aafba8cba8..f58020b785549 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -249,7 +249,11 @@ jobs:
 
       - name: test mathlib
         id: test
-        run: make -j 8 test
+        run: |
+          # Tests use parts of ProofWidgets not imported by Mathlib.
+          # Ensure everything has been built.
+          lake build ProofWidgets
+          make -j 8 test
 
       - name: lint mathlib
         id: lint
diff --git a/.github/workflows/build.yml.in b/.github/workflows/build.yml.in
index 998af8203f4f0..059fcd36bbd89 100644
--- a/.github/workflows/build.yml.in
+++ b/.github/workflows/build.yml.in
@@ -228,7 +228,11 @@ jobs:
 
       - name: test mathlib
         id: test
-        run: make -j 8 test
+        run: |
+          # Tests use parts of ProofWidgets not imported by Mathlib.
+          # Ensure everything has been built.
+          lake build ProofWidgets
+          make -j 8 test
 
       - name: lint mathlib
         id: lint
diff --git a/.github/workflows/build_fork.yml b/.github/workflows/build_fork.yml
index db68e7834f65c..98e5c5ae28b7e 100644
--- a/.github/workflows/build_fork.yml
+++ b/.github/workflows/build_fork.yml
@@ -246,7 +246,11 @@ jobs:
 
       - name: test mathlib
         id: test
-        run: make -j 8 test
+        run: |
+          # Tests use parts of ProofWidgets not imported by Mathlib.
+          # Ensure everything has been built.
+          lake build ProofWidgets
+          make -j 8 test
 
       - name: lint mathlib
         id: lint