diff --git a/decrypt_packets.c b/decrypt_packets.c
index cd01d15..642f252 100644
--- a/decrypt_packets.c
+++ b/decrypt_packets.c
@@ -17,15 +17,15 @@ int main(int argc, char *argv[]) {
 
 	uint32_t server_data_size = 0;
 	uint32_t client_data_size = 0;
+	uint8_t *server_data;
+	uint8_t *client_data;
 
-	uint8_t *server_data = read_file(server_packet_file, &server_data_size);
-	if (!server_data) {
+	if (read_file(server_packet_file, &server_data, &server_data_size)) {
 		printf("Error reading server packet data file: %s\n", server_packet_file);
 		return 1;
 	}
 
-	uint8_t *client_data = read_file(client_packet_file, &client_data_size);
-	if (!client_data) {
+	if (read_file(client_packet_file, &client_data, &client_data_size)) {
 		printf("Error reading client packet data file: %s\n", client_packet_file);
 		free(server_data);
 		return 1;
diff --git a/utils.c b/utils.c
index c593914..7d14c4c 100644
--- a/utils.c
+++ b/utils.c
@@ -3,13 +3,15 @@
 #include <string.h>
 #include <malloc.h>
 
-void* read_file(const char *filename, uint32_t *out_file_size) {
-	if (!out_file_size)
-		return NULL;
+#include "utils.h"
+
+int read_file(const char *filename, uint8_t** out_file_data, uint32_t *out_file_size) {
+	if (!out_file_size || !out_file_data)
+		return ERROR_INVALID_PARAMS;
 
 	FILE *fp = fopen(filename, "rb");
 	if (!fp)
-		return NULL;
+		return ERROR_FILE_NOT_FOUND;
 
 	fseek(fp, 0, SEEK_END);
 	*out_file_size = ftell(fp);
@@ -30,19 +32,23 @@ void* read_file(const char *filename, uint32_t *out_file_size) {
 		}
 	} while (read);
 
-	return result;
+	*out_file_data = result;
+	return SUCCESS;
 }
 
 int get_filesize(const char *filename, size_t *out_size) {
+	if (!filename || !out_size)
+		return ERROR_INVALID_PARAMS;
+
 	FILE *fp = fopen(filename, "rb");
 	if (!fp)
-		return 1;
+		return ERROR_FILE_NOT_FOUND;
 
 	fseek(fp, 0, SEEK_END);
 	*out_size = ftell(fp);
 	fclose(fp);
 
-	return 0;
+	return SUCCESS;
 }
 
 const char* path_to_filename(const char *path) {
diff --git a/utils.h b/utils.h
index 2e776d5..a51f0fe 100644
--- a/utils.h
+++ b/utils.h
@@ -3,7 +3,11 @@
 
 #include <stdint.h>
 
-void* read_file(const char *filename, uint32_t *out_file_size);
+#define SUCCESS                        0
+#define ERROR_INVALID_PARAMS           1
+#define ERROR_FILE_NOT_FOUND           2
+
+int read_file(const char *filename, uint8_t** out_file_data, uint32_t *out_file_size);
 int get_filesize(const char *filename, size_t *out_size);
 const char* path_to_filename(const char *path);
 char* append_string(const char *a, const char *b);