diff --git a/src/main/scala/config/Config.scala b/src/main/scala/config/Config.scala
index 5ae84865..1da72b77 100644
--- a/src/main/scala/config/Config.scala
+++ b/src/main/scala/config/Config.scala
@@ -23,9 +23,17 @@ abstract class View {
 }
 
 abstract class Parameters extends View {
-  final def ++ (x: Parameters):                                       Parameters = new ChainParameters(this, x)
-  final def alter(f: (View, View, View) => PartialFunction[Any,Any]): Parameters = Parameters(f) ++ this
-  final def alterPartial(f: PartialFunction[Any,Any]):                Parameters = Parameters((_,_,_) => f) ++ this
+  final def ++ (x: Parameters): Parameters =
+    new ChainParameters(this, x)
+
+  final def alter(f: (View, View, View) => PartialFunction[Any,Any]): Parameters =
+    Parameters(f) ++ this
+
+  final def alterPartial(f: PartialFunction[Any,Any]): Parameters =
+    Parameters((_,_,_) => f) ++ this
+
+  final def alterMap(m: Map[Any,Any]): Parameters =
+    new MapParameters(m) ++ this
 
   protected[config] def chain[T](site: View, tail: View, pname: Field[T]): Option[T]
   protected[config] def find[T](pname: Field[T], site: View) = chain(site, new TerminalView, pname)
@@ -69,3 +77,10 @@ private class PartialParameters(f: (View, View, View) => PartialFunction[Any,Any
     if (g.isDefinedAt(pname)) Some(g.apply(pname).asInstanceOf[T]) else tail.find(pname, site)
   }
 }
+
+private class MapParameters(map: Map[Any, Any]) extends Parameters {
+  protected[config] def chain[T](site: View, tail: View, pname: Field[T]) = {
+    val g = map.get(pname)
+    if (g.isDefined) Some(g.get.asInstanceOf[T]) else tail.find(pname, site)
+  }
+}