diff --git a/bitbake/lib/bb/cookerdata.py b/bitbake/lib/bb/cookerdata.py
index fa1de7a22f..bf9bfbf931 100644
--- a/bitbake/lib/bb/cookerdata.py
+++ b/bitbake/lib/bb/cookerdata.py
@@ -357,6 +357,9 @@ class CookerDataBuilder(object):
         # We register any handlers we've found so far here...
         for var in data.getVar('__BBHANDLERS', False) or []:
             handlerfn = data.getVarFlag(var, "filename", False)
+            if not handlerfn:
+                parselog.critical("Undefined event handler function '%s'" % var)
+                sys.exit(1)
             handlerln = int(data.getVarFlag(var, "lineno", False))
             bb.event.register(var, data.getVar(var, False),  (data.getVarFlag(var, "eventmask", True) or "").split(), handlerfn, handlerln)
 
diff --git a/bitbake/lib/bb/parse/ast.py b/bitbake/lib/bb/parse/ast.py
index d7185b1664..fa83b18981 100644
--- a/bitbake/lib/bb/parse/ast.py
+++ b/bitbake/lib/bb/parse/ast.py
@@ -344,6 +344,8 @@ def finalize(fn, d, variant = None):
     for var in d.getVar('__BBHANDLERS', False) or []:
         # try to add the handler
         handlerfn = d.getVarFlag(var, "filename", False)
+        if not handlerfn:
+            bb.fatal("Undefined event handler function '%s'" % var)
         handlerln = int(d.getVarFlag(var, "lineno", False))
         bb.event.register(var, d.getVar(var, False), (d.getVarFlag(var, "eventmask", True) or "").split(), handlerfn, handlerln)