--- a/setup.py
+++ b/setup.py
@@ -308,6 +308,7 @@ class PyBuildExt(build_ext):
             print("Failed to build these modules:")
             print_three_column(failed)
             print()
+            if cross_compiling: sys.exit(1)
 
         if self.failed_on_import:
             failed = self.failed_on_import[:]
