diff --git a/config/src/main/java/com/typesafe/config/impl/SimpleConfig.java b/config/src/main/java/com/typesafe/config/impl/SimpleConfig.java
index 2cf5bab8..924340d0 100644
--- a/config/src/main/java/com/typesafe/config/impl/SimpleConfig.java
+++ b/config/src/main/java/com/typesafe/config/impl/SimpleConfig.java
@@ -408,7 +408,7 @@ final class SimpleConfig implements Config, MergeableValue, Serializable {
                 l.add(n);
             } else {
                 throw new ConfigException.WrongType(v.origin(), path,
-                        "duration string or number of " + unit.name(),
+                        "duration string or number of milliseconds",
                         v.valueType().name());
             }
         }