diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 452544be499..691caa913dc 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -801,6 +801,7 @@ def real_work():
 
                 # Still need to clean up b/c there was an error.
                 cleanup()
+                os._exit(1)
 
             except:
                 # other exceptions just clean up and raise.