diff --git a/hdlc/hdlc_frame.c b/hdlc/hdlc_frame.c
index 40efe30..f73e0db 100644
--- a/hdlc/hdlc_frame.c
+++ b/hdlc/hdlc_frame.c
@@ -1,5 +1,4 @@
 #include "hdlc_frame.h"
-#include <stdlib.h>
 
 #define START_FLAG 0x7E
 #define END_FLAG 0x7E
@@ -15,7 +14,7 @@ void initialize_frame(HDLCFrame* frame, uint8_t address, uint8_t control, uint8_
 
 uint16_t calculate_fcs(HDLCFrame* frame) {
     uint16_t fcs = 0xFFFF;
-    uint8_t* data_bytes = malloc(frame->data_length + 2);
+    uint8_t data_bytes[MAX_FRAME_LENGTH];
     data_bytes[0] = frame->address;
     data_bytes[1] = frame->control;
 
@@ -29,41 +28,41 @@ uint16_t calculate_fcs(HDLCFrame* frame) {
         fcs &= 0xFFFF;
     }
 
-    free(data_bytes);
     return fcs;
 }
 
-void create_frame(HDLCFrame* frame, uint8_t** frame_data, size_t* frame_length) {
-    *frame_length = 4 + frame->data_length;
-    *frame_data = malloc(*frame_length);
-    (*frame_data)[0] = START_FLAG;
-    (*frame_data)[1] = frame->address;
-    (*frame_data)[2] = frame->control;
+void create_frame(HDLCFrame* frame, uint8_t* frame_data, size_t* frame_length) {
+    size_t index = 0;
+    frame_data[index++] = START_FLAG;
+    frame_data[index++] = frame->address;
+    frame_data[index++] = frame->control;
 
-    size_t index = 3;
     for (size_t i = 0; i < frame->data_length; i++) {
         uint8_t byte = frame->data[i];
         if (byte == START_FLAG || byte == END_FLAG || byte == ESCAPE_FLAG) {
-            (*frame_data)[index++] = ESCAPE_FLAG;
-            (*frame_data)[index++] = byte ^ ESCAPE_XOR;
+            frame_data[index++] = ESCAPE_FLAG;
+            frame_data[index++] = byte ^ ESCAPE_XOR;
         } else {
-            (*frame_data)[index++] = byte;
+            frame_data[index++] = byte;
         }
     }
 
     uint16_t fcs = calculate_fcs(frame);
-    (*frame_data)[index++] = fcs & 0xFF;
-    (*frame_data)[index] = END_FLAG;
+    frame_data[index++] = fcs & 0xFF;
+    frame_data[index++] = (fcs >> 8) & 0xFF;
+    frame_data[index] = END_FLAG;
+
+    *frame_length = index + 1;
 }
 
 HDLCFrame* create_u_frame(uint8_t address, uint8_t control, uint8_t* data, size_t data_length) {
-    HDLCFrame* frame = malloc(sizeof(HDLCFrame));
+    HDLCFrame* frame = (HDLCFrame*)malloc(sizeof(HDLCFrame));
     initialize_frame(frame, address, control, data, data_length);
     return frame;
 }
 
 HDLCFrame* create_s_frame(uint8_t address, uint8_t control, uint8_t* data, size_t data_length, uint8_t receive_sequence_number, uint8_t send_sequence_number) {
-    HDLCFrame* frame = malloc(sizeof(HDLCFrame));
+    HDLCFrame* frame = (HDLCFrame*)malloc(sizeof(HDLCFrame));
     initialize_frame(frame, address, control, data, data_length);
     frame->control |= (receive_sequence_number << 2) & 0xFC;
     frame->control |= (send_sequence_number << 1) & 0xFE;
@@ -71,7 +70,7 @@ HDLCFrame* create_s_frame(uint8_t address, uint8_t control, uint8_t* data, size_
 }
 
 HDLCFrame* create_i_frame(uint8_t address, uint8_t control, uint8_t* data, size_t data_length, uint8_t sequence_number) {
-    HDLCFrame* frame = malloc(sizeof(HDLCFrame));
+    HDLCFrame* frame = (HDLCFrame*)malloc(sizeof(HDLCFrame));
     initialize_frame(frame, address, control, data, data_length);
     frame->control |= (sequence_number << 1) & 0xFE;
     return frame;
diff --git a/hdlc/hdlc_frame.h b/hdlc/hdlc_frame.h
index ceae96e..09792a6 100644
--- a/hdlc/hdlc_frame.h
+++ b/hdlc/hdlc_frame.h
@@ -2,6 +2,7 @@
 #define HDLC_FRAME_H
 
 #include <stdint.h>
+#define MAX_FRAME_LENGTH 256
 
 typedef struct {
     uint8_t address;
@@ -12,10 +13,11 @@ typedef struct {
 
 void initialize_frame(HDLCFrame* frame, uint8_t address, uint8_t control, uint8_t* data, size_t data_length);
 uint16_t calculate_fcs(HDLCFrame* frame);
-void create_frame(HDLCFrame* frame, uint8_t** frame_data, size_t* frame_length);
+void create_frame(HDLCFrame* frame, uint8_t* frame_data, size_t* frame_length);
 
 HDLCFrame* create_u_frame(uint8_t address, uint8_t control, uint8_t* data, size_t data_length);
 HDLCFrame* create_s_frame(uint8_t address, uint8_t control, uint8_t* data, size_t data_length, uint8_t receive_sequence_number, uint8_t send_sequence_number);
 HDLCFrame* create_i_frame(uint8_t address, uint8_t control, uint8_t* data, size_t data_length, uint8_t sequence_number);
 
+
 #endif
\ No newline at end of file
diff --git a/hdlc/test_hdlc_frame.c b/hdlc/test_hdlc_frame.c
index 34ab052..2c8a748 100644
--- a/hdlc/test_hdlc_frame.c
+++ b/hdlc/test_hdlc_frame.c
@@ -17,30 +17,25 @@ int main() {
     size_t data_length = sizeof(data) / sizeof(data[0]);
 
     HDLCFrame* u_frame = create_u_frame(address, control, data, data_length);
-    uint8_t* u_frame_data;
+    uint8_t u_frame_data[MAX_FRAME_LENGTH];
     size_t u_frame_length;
-    create_frame(u_frame, &u_frame_data, &u_frame_length);
+    create_frame(u_frame, u_frame_data, &u_frame_length);
     print_frame(u_frame_data, u_frame_length);
-    free(u_frame_data);
-    free(u_frame);
 
-    uint8_t receive_sequence_number = 0x01;
-    uint8_t send_sequence_number = 0x02;
-    HDLCFrame* s_frame = create_s_frame(address, control, data, data_length, receive_sequence_number, send_sequence_number);
-    uint8_t* s_frame_data;
+    HDLCFrame* s_frame = create_s_frame(address, control, data, data_length, 0x01, 0x02);
+    uint8_t s_frame_data[MAX_FRAME_LENGTH];
     size_t s_frame_length;
-    create_frame(s_frame, &s_frame_data, &s_frame_length);
+    create_frame(s_frame, s_frame_data, &s_frame_length);
     print_frame(s_frame_data, s_frame_length);
-    free(s_frame_data);
-    free(s_frame);
 
-    uint8_t sequence_number = 0x03;
-    HDLCFrame* i_frame = create_i_frame(address, control, data, data_length, sequence_number);
-    uint8_t* i_frame_data;
+    HDLCFrame* i_frame = create_i_frame(address, control, data, data_length, 0x03);
+    uint8_t i_frame_data[MAX_FRAME_LENGTH];
     size_t i_frame_length;
-    create_frame(i_frame, &i_frame_data, &i_frame_length);
+    create_frame(i_frame, i_frame_data, &i_frame_length);
     print_frame(i_frame_data, i_frame_length);
-    free(i_frame_data);
+
+    free(u_frame);
+    free(s_frame);
     free(i_frame);
 
     return 0;