diff --git a/lang-parser b/lang-parser
index 8e69e96..e2f0ef7 160000
--- a/lang-parser
+++ b/lang-parser
@@ -1 +1 @@
-Subproject commit 8e69e96520290fab76a98e620d58a4478e9d0861
+Subproject commit e2f0ef7b83e0bb5cc370fe365dd4fa871a44342c
diff --git a/src/build_visitor.cpp b/src/build_visitor.cpp
index 92987c4..6cf145f 100644
--- a/src/build_visitor.cpp
+++ b/src/build_visitor.cpp
@@ -1481,32 +1481,52 @@ void BuildVisitor::Visit(TypeExpression* node) {
 
   auto suffix_node1 = current_node_.NextSibling();
 
-  // TODO: better structure // TODO: check
+  // TODO: refactor ?? // TODO: check
   if (!suffix_node1.IsNull()) {
     auto suffix_node2 = suffix_node1.NextSibling();
     if (!suffix_node2.IsNull()) {
       auto suffix_node3 = suffix_node2.NextSibling();
       if (!suffix_node3.IsNull()) {
-        current_node_ = suffix_node2;
+        if (suffix_node2.GetValue() == "_") {
+          node->array_size = 0; // dynamic array
+        } else {
+          current_node_ = suffix_node2;
+          NumberLiteral size_literal;
+          Visit(&size_literal);
+          node->array_size = size_literal.value;
 
-        NumberLiteral literal;
-        Visit(&literal);
-        node->array_size = literal.value;
-        ++excluded_child_count;
+          if (size_literal.value == 0) {
+            error_handling::HandleParsingError("Can't have zero sized arrays with constant length",
+                                                 node->base.start_position,
+                                                 node->base.end_position);
+          }
+
+          ++excluded_child_count; // literal is named child
+        }
 
         node->is_optional = true;
       } else {
         if (suffix_node1.GetValue() == "`" && suffix_node2.GetValue() == "?") {
-          node->array_size = 0;
-
-          node->is_optional = true;
+          error_handling::HandleInternalError("Array suffix should have size parameter or _",
+                                            "BuildVisitor.TypeExpression",
+                                            std::nullopt);
         } else if (suffix_node1.GetValue() == "`") {
-          current_node_ = suffix_node2;
+          if (suffix_node2.GetValue() == "_") {
+            node->array_size = 0; // dynamic array
+          } else {
+            current_node_ = suffix_node2;
+            NumberLiteral size_literal;
+            Visit(&size_literal);
+            node->array_size = size_literal.value;
 
-          NumberLiteral literal;
-          Visit(&literal);
-          node->array_size = literal.value;
-          ++excluded_child_count;
+            if (size_literal.value == 0) {
+              error_handling::HandleParsingError("Can't have zero sized arrays with constant length",
+                                                 node->base.start_position,
+                                                 node->base.end_position);
+            }
+
+            ++excluded_child_count; // literal is named child
+          }
         } else {
           error_handling::HandleInternalError("Undefined suffix (2 elements)",
                                               "BuildVisitor.TypeExpression",
@@ -1515,7 +1535,9 @@ void BuildVisitor::Visit(TypeExpression* node) {
       }
     } else {
       if (suffix_node1.GetValue() == "`") {
-        node->array_size = 0;
+        error_handling::HandleInternalError("Array suffix should have size parameter or _",
+                                            "BuildVisitor.TypeExpression",
+                                            std::nullopt);
       } else if (suffix_node1.GetValue() == "?") {
         node->is_optional = true;
       } else {
diff --git a/tests/memory.lang b/tests/memory.lang
index c0762f4..dbe541d 100644
--- a/tests/memory.lang
+++ b/tests/memory.lang
@@ -1,5 +1,5 @@
 struct \struct-with-ref =
-  & @\int`0
+  & @\int`_
 
 decl test-memory : -> \unit
 def test-memory = {
diff --git a/tests/test_code.lang b/tests/test_code.lang
index cbdc85a..6c64bff 100644
--- a/tests/test_code.lang
+++ b/tests/test_code.lang
@@ -188,7 +188,7 @@ typeclass \enum =
 
 //
 
-decl ( -- ) : \int -> \int -> \int`0
+decl ( -- ) : \int -> \int -> \int`_
 def ( -- ) : begin end = {
   var current = begin
   return (while current < end do {
@@ -252,10 +252,10 @@ def print-anything : x = \io..print: (x..show:)
 //   return a-copy
 // }
 
-struct \array 'a = & 'a`0
+struct \array 'a = & 'a`_
 
 namespace \array {
-   decl of : 'a`0 -> \array['a]
+   decl of : 'a`_ -> \array['a]
    def of : x = $array['a] & x
 }