diff --git a/.github/workflows/crystal.yml b/.github/workflows/crystal.yml
index 78c53c6..4c05903 100644
--- a/.github/workflows/crystal.yml
+++ b/.github/workflows/crystal.yml
@@ -21,7 +21,7 @@ jobs:
     - name: Install system dependencies
       run: |
         apt-get update
-        apt-get install -y cmake 
+        apt-get install -y cmake g++-9 gcc-9 
     - name: Install project dependencies
       run: shards install
     - name: Run tests
@@ -39,7 +39,7 @@ jobs:
     - name: Install system dependencies
       run: |
         apt-get update
-        apt-get install -y cmake 
+        apt-get install -y cmake g++-9 gcc-9 
 
     - name: Install project dependencies
       run: shards install