diff --git a/src/main/java/fi/solita/utils/functional/FunctionalImpl.java b/src/main/java/fi/solita/utils/functional/FunctionalImpl.java
index 6f6546b..0892bf9 100644
--- a/src/main/java/fi/solita/utils/functional/FunctionalImpl.java
+++ b/src/main/java/fi/solita/utils/functional/FunctionalImpl.java
@@ -356,7 +356,7 @@ public static <T> Pair<T, Iterable<T>> split(Iterable<T> xs) {
     
     public static final <T> Iterable<T> every(int nth, Iterable<T> xs) {
         // TODO: optimize...
-        return Functional.map(Transformers.<T>right(), Functional.filter(Transformers.<Integer>_1().andThen(Predicates.divisible(nth)), Functional.zipWithIndex(xs)));
+        return nth < 0 ? Collections.<T>emptyList() : nth == 0 ? headOption(xs) : Functional.map(Transformers.<T>right(), Functional.filter(Transformers.<Integer>_1().andThen(Predicates.divisible(nth)), Functional.zipWithIndex(xs)));
     }
     
     static final boolean isEmpty(Iterable<?> xs) {
diff --git a/src/test/java/fi/solita/utils/functional/FunctionalTest.java b/src/test/java/fi/solita/utils/functional/FunctionalTest.java
index d708369..5e64288 100644
--- a/src/test/java/fi/solita/utils/functional/FunctionalTest.java
+++ b/src/test/java/fi/solita/utils/functional/FunctionalTest.java
@@ -423,4 +423,14 @@ public void testIntersection() {
         assertEquals(newSet(2), Functional.intersection(newSet(1,2), newSet(2,3)));
         assertEquals(newSet(2), Functional.intersection(Arrays.asList(newSet(1,2), newSet(2,3))));
     }
+    
+    @Test
+    public void testEvery() {
+        assertEquals(emptyList(), newList(Functional.every(-1, newList(0,1,2,3,4,5))));
+        assertEquals(newList(0), newList(Functional.every(0, newList(0,1,2,3,4,5))));
+        assertEquals(newList(0,1,2,3,4,5), newList(Functional.every(1, newList(0,1,2,3,4,5))));
+        assertEquals(newList(0,2,4), newList(Functional.every(2, newList(0,1,2,3,4,5))));
+        assertEquals(newList(0,3), newList(Functional.every(3, newList(0,1,2,3,4,5))));
+        assertEquals(newList(0), newList(Functional.every(6, newList(0,1,2,3,4,5))));
+    }
 }