diff --git a/shperm.c b/shperm.c
index 509fe59..b28db96 100644
--- a/shperm.c
+++ b/shperm.c
@@ -9,9 +9,14 @@
 #include <pwd.h>
 #include <grp.h>
 
+#define PLEASE_ADD_ONE_EXTRA_BYTE_FOR_ZERO_TERMINATED_STRING 1
+
 #define PERMISSION_USER 2
 #define PERMISSION_GROUP 1
 #define PERMISSION_OTHERS 0
+#define PERMISSION_BYTES 3 // rwx
+#define PERMISSION_ENTITIES 3 // user group others
+const MAX_PERMISSIONS = PERMISSION_ENTITIES * PERMISSION_BYTES;
 
 typedef struct {
     char* username;
@@ -38,14 +43,15 @@ void mallocLines() {
 }
 
 void addPermission2Line(int idx, int permissions) {
-    strcpy(lines[idx].permissionStr[0], "---");
-    strcpy(lines[idx].permissionStr[1], "---");
-    strcpy(lines[idx].permissionStr[2], "---");
-    for (int i = 0; i < 9; i++) {
+    strcpy(lines[idx].permissionStr[PERMISSION_USER], "---");
+    strcpy(lines[idx].permissionStr[PERMISSION_GROUP], "---");
+    strcpy(lines[idx].permissionStr[PERMISSION_OTHERS], "---");
+    for (int i = 0; i < MAX_PERMISSIONS; i++) {
         // clear out all permissions except the i'th bit
         int tmpPermission = permissions & (1 << i);
-        int permissionUGO = i / 3;
-        int permissionRWX = (8 - i) % 3;
+        int permissionUGO = i / PERMISSION_ENTITIES;
+        // -1 because of 0-based index
+        int permissionRWX = (MAX_PERMISSIONS - i - 1) % PERMISSION_BYTES;
 
         // read
         if (tmpPermission & S_IRUSR
@@ -81,7 +87,7 @@ void addLine(char* path, int permissions, int uid, int gid) {
 
     // add user
     struct passwd* user = getpwuid(uid);
-    lines[idx].username = malloc(strlen(user->pw_name) + 1);
+    lines[idx].username = malloc(strlen(user->pw_name) + PLEASE_ADD_ONE_EXTRA_BYTE_FOR_ZERO_TERMINATED_STRING);
     strcpy(lines[idx].username, user->pw_name);
     if (maxUsername < strlen(lines[idx].username)) {
         maxUsername = strlen(lines[idx].username);
@@ -89,7 +95,7 @@ void addLine(char* path, int permissions, int uid, int gid) {
 
     // add group
     struct group* group = getgrgid(gid);
-    lines[idx].groupname = malloc(strlen(group->gr_name) + 1);
+    lines[idx].groupname = malloc(strlen(group->gr_name) + PLEASE_ADD_ONE_EXTRA_BYTE_FOR_ZERO_TERMINATED_STRING);
     strcpy(lines[idx].groupname, group->gr_name);
     if (maxGroupname < strlen(lines[idx].groupname)) {
         maxGroupname = strlen(lines[idx].groupname);
@@ -99,7 +105,7 @@ void addLine(char* path, int permissions, int uid, int gid) {
     addPermission2Line(idx, permissions);
 
     // add current path
-    lines[idx].path = malloc(strlen(path) + 1);
+    lines[idx].path = malloc(strlen(path) + PLEASE_ADD_ONE_EXTRA_BYTE_FOR_ZERO_TERMINATED_STRING);
     strcpy(lines[idx].path, path);
 }