diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 5c81d3128e6..3507807373e 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -832,6 +832,10 @@ def real_work():
                 cleanup()
                 raise
 
+        # Set parallelism before starting build.
+        self.make_jobs = make_jobs
+
+        # Do the build.
         spack.build_environment.fork(self, real_work)
 
         # Once everything else is done, run post install hooks