diff --git a/Lib/guile/guile.swg b/Lib/guile/guile.swg
index 227ec2767..3d7cfe653 100644
--- a/Lib/guile/guile.swg
+++ b/Lib/guile/guile.swg
@@ -252,7 +252,7 @@ void SWIG_Guile_RegisterTypes(_swig_type_info **table)
     _swig_type_info *type = *table;
     char *origname = type->name;
     /* Register datatype itself and store pointer back */
-    type->tag = SWIG_RegisterType(origname, NULL /* FIXME: prettyname */);
+    type->tag = SWIG_RegisterType(origname, type->str);
     /* Register compatible types */
     for (type++; type->name; type++)
       SWIG_RegisterMapping(origname, type->name, type->converter);
diff --git a/Lib/guile/guiledec.swg b/Lib/guile/guiledec.swg
index c6cf1726b..e6ae7032b 100644
--- a/Lib/guile/guiledec.swg
+++ b/Lib/guile/guiledec.swg
@@ -50,6 +50,7 @@ typedef struct SwigPtrType SwigPtrType;
 typedef struct _swig_type_info {
   char  *name;
   void *(*converter)(void *);
+  char  *str;
   size_t tag;
 } _swig_type_info;