diff --git a/.github/workflows/osrm-backend.yml b/.github/workflows/osrm-backend.yml
index 17a549452..5fc382b72 100644
--- a/.github/workflows/osrm-backend.yml
+++ b/.github/workflows/osrm-backend.yml
@@ -138,7 +138,7 @@ jobs:
             runs-on: ubuntu-20.04
             BUILD_TOOLS: ON
             BUILD_TYPE: Debug
-            CLANG_VERSION: 6.0
+            CLANG_VERSION: "6.0"
             CUCUMBER_TIMEOUT: 60000
 
           - name: clang-11.0-debug-clang-tidy
@@ -147,7 +147,7 @@ jobs:
             runs-on: ubuntu-20.04
             BUILD_TOOLS: ON
             BUILD_TYPE: Debug
-            CLANG_VERSION: 11.0
+            CLANG_VERSION: "11.0"
             CUCUMBER_TIMEOUT: 60000
             ENABLE_CLANG_TIDY: ON
 
@@ -157,7 +157,7 @@ jobs:
             runs-on: ubuntu-20.04
             BUILD_TOOLS: ON
             BUILD_TYPE: Release
-            CLANG_VERSION: 11.0
+            CLANG_VERSION: "11.0"
             ENABLE_CONAN: ON
             ENABLE_SANITIZER: ON
 
@@ -167,7 +167,7 @@ jobs:
             runs-on: ubuntu-20.04
             BUILD_TOOLS: ON
             BUILD_TYPE: Release
-            CLANG_VERSION: 6.0
+            CLANG_VERSION: "6.0"
             ENABLE_CONAN: ON
 
           # - name: gcc-11-release