diff --git a/src/main/java/com/annimon/ownlang/modules/functional/functional_foreach.java b/src/main/java/com/annimon/ownlang/modules/functional/functional_foreach.java
index 4e0ceed..239e3f3 100644
--- a/src/main/java/com/annimon/ownlang/modules/functional/functional_foreach.java
+++ b/src/main/java/com/annimon/ownlang/modules/functional/functional_foreach.java
@@ -20,14 +20,14 @@ public final class functional_foreach implements Function {
             for (Value element : array) {
                 consumer.execute(element);
             }
-            return NumberValue.ZERO;
+            return array;
         }
         if (container.type() == Types.MAP) {
             final MapValue map = (MapValue) container;
             for (Map.Entry<Value, Value> element : map) {
                 consumer.execute(element.getKey(), element.getValue());
             }
-            return NumberValue.ZERO;
+            return map;
         }
         throw new TypeException("Invalid first argument. Array or map expected");
     }
diff --git a/src/main/java/com/annimon/ownlang/modules/functional/functional_stream.java b/src/main/java/com/annimon/ownlang/modules/functional/functional_stream.java
index 82e590a..544fe49 100644
--- a/src/main/java/com/annimon/ownlang/modules/functional/functional_stream.java
+++ b/src/main/java/com/annimon/ownlang/modules/functional/functional_stream.java
@@ -29,7 +29,7 @@ public final class functional_stream implements Function {
         private final ArrayValue container;
 
         public StreamValue(ArrayValue container) {
-            super(13);
+            super(15);
             this.container = container;
             init();
         }
@@ -41,6 +41,7 @@ public final class functional_stream implements Function {
             set("sortBy", wrapIntermediate(new functional_sortby()));
             set("takeWhile", wrapIntermediate(new functional_filter(true)));
             set("dropWhile", wrapIntermediate(new functional_dropwhile()));
+            set("peek", wrapIntermediate(new functional_foreach()));
             set("skip", this::skip);
             set("limit", this::limit);
             set("custom", this::custom);
diff --git a/src/test/resources/modules/functional/stream.own b/src/test/resources/modules/functional/stream.own
index 19fa66d..5d60078 100644
--- a/src/test/resources/modules/functional/stream.own
+++ b/src/test/resources/modules/functional/stream.own
@@ -44,6 +44,19 @@ def testCustom() {
   assertEquals([5,6,4,2], stream(data).custom(::reverse).toArray())
 }
 
+def testPeek() {
+  data = [2,3,4,5,6,7]
+  expected = [2,4,6]
+  index = 0
+
+  actual = stream(data)
+    .filter(def(x) = x % 2 == 0)
+    .peek(def(x) = assertEquals(expected[index++], x))
+    .toArray()
+  assertEquals(expected, actual)
+  assertEquals(length(expected), index)
+}
+
 def reverse(container) {
   size = length(container)
   result = newarray(size)