diff --git a/intersect.go b/intersect.go
index 2df0e741..f5f56ee1 100644
--- a/intersect.go
+++ b/intersect.go
@@ -102,6 +102,7 @@ func Intersect[T comparable, Slice ~[]T](list1 Slice, list2 Slice) Slice {
 	for i := range list2 {
 		if _, ok := seen[list2[i]]; ok {
 			result = append(result, list2[i])
+			delete(seen, list2[i])
 		}
 	}
 
diff --git a/intersect_test.go b/intersect_test.go
index 53911599..8ab27174 100644
--- a/intersect_test.go
+++ b/intersect_test.go
@@ -181,12 +181,14 @@ func TestIntersect(t *testing.T) {
 	result3 := Intersect([]int{0, 1, 2, 3, 4, 5}, []int{-1, 6})
 	result4 := Intersect([]int{0, 6}, []int{0, 1, 2, 3, 4, 5})
 	result5 := Intersect([]int{0, 6, 0}, []int{0, 1, 2, 3, 4, 5})
+	result6 := Intersect([]int{0, 1, 2, 3, 4, 5}, []int{0, 1, 1})
 
 	is.Equal(result1, []int{0, 2})
 	is.Equal(result2, []int{0})
 	is.Equal(result3, []int{})
 	is.Equal(result4, []int{0})
 	is.Equal(result5, []int{0})
+	is.Equal(result6, []int{0, 1})
 
 	type myStrings []string
 	allStrings := myStrings{"", "foo", "bar"}