diff --git a/setup.py b/setup.py
index 9023b9fa3..377a7689d 100755
--- a/setup.py
+++ b/setup.py
@@ -126,6 +126,8 @@ class build_ext_options:
 
 class build_ext_subclass(build_ext, build_ext_options):
     def build_extensions(self):
+        if not self.parallel:
+            self.parallel = int(os.environ.get("SPACY_NUM_BUILD_JOBS", 1))
         build_ext_options.build_options(self)
         build_ext.build_extensions(self)