diff --git a/include/tlibc/collections/List.h b/include/tlibc/collections/List.h
index 2908a66..b7cd942 100755
--- a/include/tlibc/collections/List.h
+++ b/include/tlibc/collections/List.h
@@ -21,6 +21,8 @@ List_ List_alloc_size(u32 initial_size);
 
 List_ List_copy(List_ src);
 
+// alloc bigger buffer if size + size_to_add won't fit in current
+void List_increaseCapacity_size(List_* self, u32 size_to_add);
 void* List_expand_size(List_* self, u32 size_to_add);
 #define List_push(SELF, T, VALUE) *(T*)(List_expand_size(SELF, sizeof(T))) = VALUE
 #define List_pushMany(SELF, T, VALUES_PTR, COUNT) List_push_size(SELF, VALUES_PTR, (COUNT) * sizeof(T))
@@ -30,4 +32,6 @@ void List_push_size(List_* self, void* values, u32 size);
 bool List_removeAt_size(List_* self, u32 i, u32 remove_size);
 
 #define List_len(SELF, T) (SELF.size / sizeof(T))
+#define List_index(SELF, T, I) ((T*)SELF.data)[I]
+
 #define List_castTo_Array(SELF) Array_construct_size(SELF.data, SELF.size)
diff --git a/include/tlibc/string/StringBuilder.h b/include/tlibc/string/StringBuilder.h
index 8e46689..917923f 100755
--- a/include/tlibc/string/StringBuilder.h
+++ b/include/tlibc/string/StringBuilder.h
@@ -16,8 +16,10 @@ void StringBuilder_destroy(StringBuilder* b);
 static inline StringBuilder StringBuilder_copy(const StringBuilder* b){
     return (StringBuilder) { .buffer = List_copy(b->buffer) };
 }
-static inline void StringBuilder_expand(StringBuilder* b, u32 size_to_add){
-    List_expand_size(&b->buffer, size_to_add);
+
+// alloc bigger buffer if size + size_to_add won't fit in current
+static inline void StringBuilder_increaseCapacity(StringBuilder* b, u32 size_to_add){
+    List_increaseCapacity_size(&b->buffer, size_to_add);
 }
 
 
diff --git a/src/collections/List.c b/src/collections/List.c
index 94a9b4b..5e9640c 100755
--- a/src/collections/List.c
+++ b/src/collections/List.c
@@ -14,19 +14,28 @@ List_ List_copy(const List_ src){
     return copy;
 }
 
-void* List_expand_size(List_* self, u32 size_to_add){
+void List_increaseCapacity_size(List_* self, u32 size_to_add){
     u32 occupied_size = self->size;
-    u32 expanded_alloc_size = self->allocated_size;
-    if(expanded_alloc_size == 0)
-        expanded_alloc_size = 64;
-    self->size += size_to_add;
-    while(self->size > expanded_alloc_size){
-        expanded_alloc_size *= 2;
+    u32 expanded_size = occupied_size + size_to_add;
+    
+    if(self->allocated_size < expanded_size) {
+        u32 expanded_alloc_size = self->allocated_size;
+        if(expanded_alloc_size == 0)
+            expanded_alloc_size = 32;
+        while(expanded_alloc_size < expanded_size){
+            expanded_alloc_size *= 2;
+        }
+        // if self->data is null, realloc acts like malloc
+        self->data = realloc(self->data, expanded_alloc_size);
+        self->allocated_size = expanded_alloc_size;
     }
-    // if self->data is null, realloc acts like malloc
-    self->data = realloc(self->data, expanded_alloc_size);
-    self->allocated_size = expanded_alloc_size;
-    return (u8*)(self->data) + occupied_size;
+}
+
+void* List_expand_size(List_* self, u32 size_to_add){
+    List_increaseCapacity_size(self, size_to_add);
+    u8* empty_cell_ptr = (u8*)self->data + self->size;
+    self->size += size_to_add;
+    return empty_cell_ptr;
 }
 
 void List_push_size(List_* self, void* values, u32 size){
diff --git a/src/errors.c b/src/errors.c
index 147d2c0..673d247 100755
--- a/src/errors.c
+++ b/src/errors.c
@@ -8,7 +8,7 @@ Error* Error_create(const char* msg, bool is_msg_on_heap, ErrorCallPos p){
     e->msg = str_construct((char*)(void*)msg, strlen(msg), true);
     e->is_msg_on_heap = is_msg_on_heap;
     e->call_stack = List_alloc(ErrorCallPos, 16);
-    List_push(&e->call_stack, ErrorCallPos, p);
+    Error_addCallPos(e, p);
     return e;
 }