diff --git a/lib/bb/data.py b/lib/bb/data.py
index 5fdcdb04..b12972c0 100644
--- a/lib/bb/data.py
+++ b/lib/bb/data.py
@@ -378,7 +378,7 @@ def generate_dependencies(d, ignored_vars):
     mod_funcs = set(bb.codeparser.modulecode_deps.keys())
     keys = set(key for key in d if not key.startswith("__")) | mod_funcs
     shelldeps = set(key for key in d.getVar("__exportlist", False) if bb.utils.to_boolean(d.getVarFlag(key, "export")) and not bb.utils.to_boolean(d.getVarFlag(key, "unexport")))
-    varflagsexcl = d.getVar('BB_SIGNATURE_EXCLUDE_FLAGS')
+    varflagsexcl = (d.getVar('BB_SIGNATURE_EXCLUDE_FLAGS') or "").split()
 
     codeparserd = d.createCopy()
     for forced in (d.getVar('BB_HASH_CODEPARSER_VALS') or "").split():