diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index ffe76fb05..449e89ecd 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -41,7 +41,7 @@ jobs:
 
   - task: Cache@2
     inputs:
-      key: '"ccache-wheels-v2020.05.12" | $(Agent.OS) | "$(python.version)"'
+      key: '"ccache-wheels-v2020.08.08" | $(Agent.OS) | "$(python.version)"'
       path: $(CCACHE_DIR)
     displayName: ccache
 
@@ -136,7 +136,7 @@ jobs:
 
   - task: Cache@2
     inputs:
-      key: '"ccache-v2020.05.12" | $(Agent.OS) | "$(python.version)"'
+      key: '"ccache-v2020.08.08" | $(Agent.OS) | "$(python.version)"'
       path: $(CCACHE_DIR)
     displayName: ccache
 
diff --git a/setup.py b/setup.py
index 1c2dd5e0e..8586ac9c4 100755
--- a/setup.py
+++ b/setup.py
@@ -114,7 +114,7 @@ def install_dependencies(self):
         if os.path.exists(dir_pybind11):
             return 0
         os.mkdir(dir_pybind11)
-        subprocess.check_call(['git', 'clone',
+        subprocess.check_call(['git', 'clone', '--branch', 'v2.5.0',
                                'https://github.com/pybind/pybind11.git',
                                dir_pybind11])