diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 9dfd8bf01f2..d87607a8dd3 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -2319,8 +2319,13 @@ def do_activate(self, view=None, with_dependencies=True, verbose=True):
 
         extensions_layout = view.extensions_layout
 
-        extensions_layout.check_extension_conflict(
-            self.extendee_spec, self.spec)
+        try:
+            extensions_layout.check_extension_conflict(
+                self.extendee_spec, self.spec)
+        except spack.directory_layout.ExtensionAlreadyInstalledError as e:
+            # already installed, let caller know
+            tty.msg(e.message)
+            return
 
         # Activate any package dependencies that are also extensions.
         if with_dependencies: