diff --git a/vlib/builtin/map.v b/vlib/builtin/map.v
index 948a18d517..950657aad0 100644
--- a/vlib/builtin/map.v
+++ b/vlib/builtin/map.v
@@ -59,6 +59,14 @@ mut:
 	value voidptr
 }
 
+// Dynamic array with very low growth factor
+struct DenseArray {
+mut:
+	data &KeyValue
+	cap  u32
+	size u32
+}
+
 fn new_map(n, value_bytes int) map {
 	probe_hash_bytes := sizeof(u32) * init_capicity
 	key_value_bytes := sizeof(KeyValue) * init_capicity
diff --git a/vlib/compiler/cgen.v b/vlib/compiler/cgen.v
index 37975eeb0d..bf9022445a 100644
--- a/vlib/compiler/cgen.v
+++ b/vlib/compiler/cgen.v
@@ -401,7 +401,7 @@ fn (v &V) type_definitions() string {
 	mut types := []Type // structs that need to be sorted
 	mut builtin_types := []Type // builtin types
 	// builtin types need to be on top
-	builtins := ['string', 'array', 'map', 'Option']
+	builtins := ['string', 'array', 'KeyValue', 'DenseArray', 'map', 'Option']
 	for builtin in builtins {
 		typ := v.table.typesmap[builtin]
 		builtin_types << typ