diff --git a/src/utils.cpp b/src/utils.cpp
index 595dc7a..421fc3e 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -48,8 +48,10 @@
         return "an unsigned integer";
     case yang::LeafDataTypes::Enum:
         return "an enum";
+    case yang::LeafDataTypes::IdentityRef:
+        return "an identity";
     default:
-        return "";
+        throw std::runtime_error("leafDataTypeToString: unsupported leaf data type");
     }
 }