--- a/src/context.cpp	Mon Dec 19 15:32:32 2016 -0800
+++ b/src/context.cpp	Mon Dec 19 16:35:49 2016 -0800
@@ -1002,6 +1002,7 @@
 
 
 const char *CONTEXT::find_dkim_signer(const char *name) {
+    if (!name) return NULL;
     string_map::iterator i = dkim_signer_names.find(name);
     if (i != dkim_signer_names.end()) return (*i).second;
     if (parent) return parent->find_dkim_signer(name);
@@ -1010,6 +1011,7 @@
 
 
 DKIMP CONTEXT::find_dkim_from(const char *name) {
+    if (!name) return NULL;
     dkimp_map::iterator i = dkim_from_names.find(name);
     if (i != dkim_from_names.end()) return (*i).second;
     if (parent) return parent->find_dkim_from(name);