diff --git a/lib/spack/spack/hooks/autopush.py b/lib/spack/spack/hooks/autopush.py
index b49f741ad9..1974c8d3ab 100644
--- a/lib/spack/spack/hooks/autopush.py
+++ b/lib/spack/spack/hooks/autopush.py
@@ -12,6 +12,10 @@
 def post_install(spec, explicit):
     # Push package to all buildcaches with autopush==True
 
+    # Do nothing if spec is an external package
+    if spec.external:
+        return
+
     # Do nothing if package was not installed from source
     pkg = spec.package
     if pkg.installed_from_binary_cache: