diff --git a/tools/genv8constants.py b/tools/genv8constants.py
index cb648d39ce7a18..64370ad29611c0 100755
--- a/tools/genv8constants.py
+++ b/tools/genv8constants.py
@@ -113,3 +113,5 @@ def out_define():
 
 #endif /* V8_CONSTANTS_H */
 """)
+
+outfile.close()