diff --git a/kconfiglib.py b/kconfiglib.py
index a50312e..e6e8bc3 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -2612,7 +2612,7 @@ def _parse_assignment(self, s):
             else:
                 break
 
-        if s.isspace():
+        if not s or s.isspace():
             # We also accept a bare macro on a line (e.g.
             # $(warning-if,$(foo),ops)), provided it expands to a blank string
             return