1 files changed, 4 insertions, 2 deletions
diff --git a/src/engine/SCons/Sig/MD5.py b/src/engine/SCons/Sig/MD5.py
index 5239dab..c50dbb7 100644
--- a/src/engine/SCons/Sig/MD5.py
+++ b/src/engine/SCons/Sig/MD5.py
@@ -78,9 +78,11 @@ def collect(signatures):
 def signature(obj):
     """Generate a signature for an object
     """
-    if not hasattr(obj, 'get_contents'):
+    try:
+        contents = str(obj.get_contents())
+    except AttributeError:
         raise AttributeError, "unable to fetch contents of '%s'" % str(obj)
-    return hexdigest(md5.new(str(obj.get_contents())).digest())
+    return hexdigest(md5.new(contents).digest())
 
 def to_string(signature):
     """Convert a signature to a string"""