diff --git a/tools/patman/test.py b/tools/patman/test.py
index cc61c20..889e186 100644
--- a/tools/patman/test.py
+++ b/tools/patman/test.py
@@ -72,12 +72,12 @@
 '''
         out = ''
         inhandle, inname = tempfile.mkstemp()
-        infd = os.fdopen(inhandle, 'w')
+        infd = os.fdopen(inhandle, 'w', encoding='utf-8')
         infd.write(data)
         infd.close()
 
         exphandle, expname = tempfile.mkstemp()
-        expfd = os.fdopen(exphandle, 'w')
+        expfd = os.fdopen(exphandle, 'w', encoding='utf-8')
         expfd.write(expected)
         expfd.close()