diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 3d95417..acdccb6 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -30,6 +30,9 @@ jobs:
 
       - uses: actions/checkout@v4
 
+      - name: fetch mathlib cache
+        run: lake exe cache get
+
       - name: build project
         run: just build
 
@@ -63,6 +66,9 @@ jobs:
 
       - uses: actions/checkout@v4
 
+      - name: fetch mathlib cache
+        run: lake exe cache get
+
       - name: build project
         run: just build