diff --git a/security/generate_certdata.py b/security/generate_certdata.py
index a732ccaa825c..645857cb2135 100644
--- a/security/generate_certdata.py
+++ b/security/generate_certdata.py
@@ -4,8 +4,12 @@
 # and moz.build `GENERATED_FILES` semantics.
 
 import buildconfig
+import os
 import subprocess
 
 def main(output, *inputs):
-    output.write(subprocess.check_output([buildconfig.substs['PERL']] + list(inputs)))
+    env=dict(os.environ)
+    env['PERL'] = buildconfig.substs['PERL']
+    output.write(subprocess.check_output([buildconfig.substs['PYTHON'],
+                 inputs[0], inputs[2]], env=env))
     return None