diff --git a/bitbake/lib/bb/siggen.py b/bitbake/lib/bb/siggen.py
index 0862cff78a..3a7dac4cb7 100644
--- a/bitbake/lib/bb/siggen.py
+++ b/bitbake/lib/bb/siggen.py
@@ -367,7 +367,7 @@ def compare_sigfiles(a, b, recursecb = None):
     output = []
 
     with open(a, 'rb') as f:
-        p1 = pickle.Unpickler(ff)
+        p1 = pickle.Unpickler(f)
         a_data = p1.load()
     with open(b, 'rb') as f:
         p2 = pickle.Unpickler(f)