diff --git a/modules/conop/src/rule_based.cc b/modules/conop/src/rule_based.cc
index 11dac390e7cec4d3a773a6080ff0852040a6944d..2a18ddb20360158baf6d1ac950568dfa05058ff5 100644
--- a/modules/conop/src/rule_based.cc
+++ b/modules/conop/src/rule_based.cc
@@ -179,11 +179,11 @@ void RuleBasedProcessor::ProcessUnkAtoms(DiagnosticsPtr diags,
 
 String RuleBasedProcessor::ToString() const {
   std::stringstream ss;
-  ss << "RuleBasedProcesor(" << this->OptionsToString() 
+  ss << "RuleBasedProcessor(" << this->OptionsToString() 
      << ", fix_element=" << (fix_element_ ? "True" : "False")
      << ", strict_hydrogens=" << (strict_hydrogens_ ? "True" : "False")
      << ", unk_res_treatment='" << StringFromConopAction(unk_res_treatment_)
-     << ", unk_atom_treatment'=" << StringFromConopAction(unk_atom_treatment_)
+     << "', unk_atom_treatment='" << StringFromConopAction(unk_atom_treatment_)
      << "')";
   return ss.str();
 }