diff --git a/emsdk b/emsdk
index 5fca9bf..94d1e37 100755
--- a/emsdk
+++ b/emsdk
@@ -692,7 +692,7 @@ class Tool:
   def __init__(self, data):
     # Convert the dictionary representation of the tool in 'data' to members of this class for convenience.
     for key in data:
-      if sys.version_info < (3,) and isinstance(data[key], str):
+      if sys.version_info < (3,) and isinstance(data[key], unicode):
         setattr(self, key, data[key].encode('Latin-1'))
       else:
         setattr(self, key, data[key])