diff --git a/clox/src/chunk.c b/clox/src/chunk.c
index f368dec..297dcb7 100644
--- a/clox/src/chunk.c
+++ b/clox/src/chunk.c
@@ -1,9 +1,10 @@
 #include <stdlib.h>
 
 #include "chunk.h"
-#include "memory.h"  
+#include "memory.h"
+#include "vm.h"
 
-void initChunk(Chunk* chunk) {
+void initChunk(Chunk *chunk) {
   chunk->count = 0;
   chunk->capacity = 0;
   chunk->code = NULL;
@@ -11,18 +12,19 @@ void initChunk(Chunk* chunk) {
   initValueArray(&chunk->constants);
 }
 
-void freeChunk(Chunk* chunk) {
+void freeChunk(Chunk *chunk) {
   FREE_ARRAY(uint8_t, chunk->code, chunk->capacity);
   FREE_ARRAY(int, chunk->lines, chunk->capacity);
   freeValueArray(&chunk->constants);
   initChunk(chunk);
 }
 
-void writeChunk(Chunk* chunk, uint8_t byte, int line) {
+void writeChunk(Chunk *chunk, uint8_t byte, int line) {
   if (chunk->capacity < chunk->count + 1) {
     int oldCapacity = chunk->capacity;
     chunk->capacity = GROW_CAPACITY(oldCapacity);
-    chunk->code = GROW_ARRAY(uint8_t, chunk->code, oldCapacity, chunk->capacity);
+    chunk->code =
+        GROW_ARRAY(uint8_t, chunk->code, oldCapacity, chunk->capacity);
     chunk->lines = GROW_ARRAY(int, chunk->lines, oldCapacity, chunk->capacity);
   }
 
@@ -31,7 +33,9 @@ void writeChunk(Chunk* chunk, uint8_t byte, int line) {
   chunk->count++;
 }
 
-int addConstant(Chunk* chunk, Value value) {
+int addConstant(Chunk *chunk, Value value) {
+  push(value);
   writeValueArray(&chunk->constants, value);
+  pop();
   return chunk->constants.count - 1;
 }
diff --git a/clox/src/object.c b/clox/src/object.c
index 5f2bdde..376742f 100644
--- a/clox/src/object.c
+++ b/clox/src/object.c
@@ -58,7 +58,11 @@ static ObjString *allocateString(char *chars, int length, uint32_t hash) {
   string->length = length;
   string->chars = chars;
   string->hash = hash;
+
+  push(OBJ_VAL(string));
   tableSet(&vm.strings, string, NIL_VAL);
+  pop();
+
   return string;
 }
 
diff --git a/clox/src/vm.c b/clox/src/vm.c
index c9556b2..601b128 100644
--- a/clox/src/vm.c
+++ b/clox/src/vm.c
@@ -163,8 +163,8 @@ static bool isFalsey(Value value) {
 }
 
 static void concatenate() {
-  ObjString *b = AS_STRING(pop());
-  ObjString *a = AS_STRING(pop());
+  ObjString *b = AS_STRING(peek(0));
+  ObjString *a = AS_STRING(peek(1));
 
   int length = a->length + b->length;
   char *chars = ALLOCATE(char, length + 1);
@@ -173,6 +173,8 @@ static void concatenate() {
   chars[length] = '\0';
 
   ObjString *result = takeString(chars, length);
+  pop();
+  pop();
   push(OBJ_VAL(result));
 }