diff --git a/SWIG/Lib/ruby/rubyerrors.swg b/SWIG/Lib/ruby/rubyerrors.swg
index fe5ce8bd0..5de459943 100644
--- a/SWIG/Lib/ruby/rubyerrors.swg
+++ b/SWIG/Lib/ruby/rubyerrors.swg
@@ -6,6 +6,10 @@
 
 %insert("header") %{
 
+/* Define custom error for SWIG_NullReferenceError since Ruby does not have a 
+   built-in error that seems appropriate. */
+static VALUE rb_eNullReferenceError = rb_define_class("NullReferenceError", rb_eRuntimeError);
+
 SWIGINTERN VALUE
 SWIG_Ruby_ErrorType(int SWIG_code) {
   VALUE type;
@@ -43,6 +47,9 @@ SWIG_Ruby_ErrorType(int SWIG_code) {
   case SWIG_AttributeError:
     type = rb_eRuntimeError;
     break;
+  case SWIG_NullReferenceError:
+    type = rb_eNullReferenceError;
+    break;
   case SWIG_UnknownError:
     type = rb_eRuntimeError;
     break;
@@ -52,6 +59,4 @@ SWIG_Ruby_ErrorType(int SWIG_code) {
   return type;
 }
 
-%}
-
-
+%}
\ No newline at end of file