diff --git a/src/python/pants/engine/native.py b/src/python/pants/engine/native.py
index afa4077..69879a7 100644
--- a/src/python/pants/engine/native.py
+++ b/src/python/pants/engine/native.py
@@ -230,11 +230,12 @@ extern "Python" {
 
 def get_build_cflags():
   """Synthesize a CFLAGS env var from the current python env for building of C modules."""
-  return '{} {} -I{}'.format(
+  cflags = '{} {} -I{}'.format(
     sysconfig.get_config_var('BASECFLAGS'),
     sysconfig.get_config_var('OPT'),
     sysconfig.get_path('include')
   )
+  return re.sub(r'\s+', ' ', cflags)
 
 
 def bootstrap_c_source(output_dir, module_name=NATIVE_ENGINE_MODULE):