diff --git a/core/src/list.c b/core/src/list.c
index 68a416b..d53cb6e 100644
--- a/core/src/list.c
+++ b/core/src/list.c
@@ -161,3 +161,18 @@ void* list_iterator_begin(List* self) {
 void* list_iterator_end(List* self) {
     return list_at_unchecked(self, self->len);
 }
+
+size_t list_contains(List* self, void* query) {
+    union {
+        uint8_t* as_byte;
+        void* as_void;
+    } data = {
+        .as_void = self->data
+    };
+    for(size_t i = 0; i < self->len; ++i) {
+        if(memcmp(data.as_byte + i * self->element_size, query, self->element_size) == 0) {
+            return i;
+        }
+    }
+    return self->len;
+}
diff --git a/core/src/list.h b/core/src/list.h
index 6f8789f..e79e206 100644
--- a/core/src/list.h
+++ b/core/src/list.h
@@ -26,6 +26,8 @@ extern void list_erase(List* self, size_t at);
 extern void* list_iterator_begin(List* self);
 extern void* list_iterator_end(List* self);
 
+extern size_t list_contains(List* self, void* query);
+
 #define list_from_type(T) list_init(sizeof(T))
 #define list_foreach(T, iter, list) for(T iter = list_iterator_begin(list); iter != (T)list_iterator_end(list); ++iter)
 #define list_at_as(T, __list, __i) ((T*)(list_at(__list, __i)))