Index: lib/propoffsets.c
===================================================================
--- lib/propoffsets.c	(revision 3697)
+++ lib/propoffsets.c	(working copy)
@@ -39,13 +39,21 @@
     Property *prop = g_ptr_array_index(props,i);
     const PropOffset *ofs;
     for (ofs = offsets; ofs->name ; ofs++) {
-      if ((prop->name_quark == ofs->name_quark) &&
-          (prop->type_quark == ofs->type_quark)) {
+      /* Two props cannot have the same name but different types. */
+      if (prop->name_quark == ofs->name_quark) {
+        if (prop->type_quark != ofs->type_quark) {
+          g_printerr("Property name: %s\n", prop->name);
+          g_printerr("Property type: %s\n", prop->type);
+          g_printerr("Offset type: %s\n", ofs->type);
+          g_assert(FALSE &&
+                   "Property type mismatch when setting from offsets");
+        }
+
         /* beware of props not set, see PROP_FLAG_OPTIONAL */
         if ((prop->experience & PXP_NOTSET) == 0)
           prop->ops->set_from_offset(prop,base,ofs->offset,ofs->offset2);
         break;
-      }                                    
+      }
     }
   }
 }