diff --git a/pyfakefs/fake_filesystem.py b/pyfakefs/fake_filesystem.py
index ec3089d5..b3a2833c 100644
--- a/pyfakefs/fake_filesystem.py
+++ b/pyfakefs/fake_filesystem.py
@@ -296,7 +296,7 @@ def _SetInitialContents(self, contents):
     elif isinstance(contents, Hexlified):
       st_size = len(contents)
     else:
-      st_size = len(contents.encode('utf=8'))
+      st_size = len(contents.encode('utf-8'))
 
     if self.contents:
       self.SetSize(0)