diff --git a/iso/boot/kernel.elf b/iso/boot/kernel.elf
index 58988fc..519ef6b 100755
Binary files a/iso/boot/kernel.elf and b/iso/boot/kernel.elf differ
diff --git a/makefile b/makefile
index 1df1132..b619ecb 100644
--- a/makefile
+++ b/makefile
@@ -1,5 +1,5 @@
 CC = i386-elf-7.5.0-Linux-x86_64/bin/i386-elf-gcc
-CFLAGS = -Wall -Wextra -Wno-div-by-zero -Wno-builtin-declaration-mismatch -c -I src/
+CFLAGS = -Wall -Wextra -Wno-builtin-declaration-mismatch -c -I src/
 LDFLAGS = -T link.ld -melf_i386
 AS = nasm
 ASFLAGS = -f elf
diff --git a/src/kernel/shell.c b/src/kernel/shell.c
index 815fe5a..340f623 100644
--- a/src/kernel/shell.c
+++ b/src/kernel/shell.c
@@ -4,59 +4,68 @@
 #include "../programs/programs.h"
 
 #define BUFFER_SIZE 256
+#define MAX_COMMANDS 16
+
+typedef void (*command_func_t)();
+
+typedef struct
+{
+	const char* name;
+	command_func_t function;
+} shell_command_t;
+
+shell_command_t shell_commands[MAX_COMMANDS];
+int command_count = 0;
+
+void register_command(const char* name, command_func_t function)
+{
+	if (command_count < MAX_COMMANDS)
+	{
+		shell_commands[command_count].name = name;
+		shell_commands[command_count].function = function;
+		command_count++;
+	}
+}
+
+command_func_t find_command(const char* name)
+{
+	for (int i=0; i < command_count; i++)
+	{
+		if (strcmp(name, shell_commands[i].name) == 0) 
+			return shell_commands[i].function;
+	}
+	return 0;
+}
 
 void shell_install()
 {
-  while (1) // Bad!!
+  register_command("help", program_help);
+  register_command("panic", program_panic);
+  register_command("words", program_words);
+  register_command("primes", program_primes);
+  register_command("rainbow", program_rainbow);
+  register_command("clear", program_clear);
+  register_command("math", program_math);
+  register_command("bf", program_bf);
+  register_command("uptime", program_uptime);
+  
+  for (;;)
   {
     char input_buffer[BUFFER_SIZE];
     colorputs("blankos> ", 9);
     get_input(input_buffer, BUFFER_SIZE);
     puts("\n");
-    
-    // Childish shell
-    if (strcmp(input_buffer, "") == 0)
-    {
-	continue;
+
+    if (strcmp(input_buffer, "") == 0) {
+    	continue;
     }
-    else if (strcmp(input_buffer, "help") == 0)
+
+    command_func_t command = find_command(input_buffer);
+    if (command)
     {
-        printf("help\tpanic\twords\tprimes\trainbow\tclear\nmath\tbf\tuptime\n");
-    }
-    else if (strcmp(input_buffer, "panic") == 0)
-    {
-	printf("%d", 4/0);
-    }
-    else if (strcmp(input_buffer, "words") == 0)
-    {
-	    program_words();
-    }
-    else if (strcmp(input_buffer, "primes") == 0)
-    {
-	    program_primes();
-    }
-    else if (strcmp(input_buffer, "rainbow") == 0)
-    {
-	program_rainbow();
-    }
-    else if (strcmp(input_buffer, "clear") == 0)
-    {
-	program_clear();
-    }
-    else if (strcmp(input_buffer, "math") == 0)
-    {
-	    program_math();
-    }
-    else if (strcmp(input_buffer, "bf") == 0)
-    {
-	    program_bf();
-    }
-    else if (strcmp(input_buffer, "uptime") == 0)
-    {
-	    program_uptime();
-    }
-    else {
-	printf("Unknown command %s\n", input_buffer);
+	    command();
+    } else {
+	    printf("Unknown command %s\n", input_buffer);
     }
   }
 }
diff --git a/src/libc/string.c b/src/libc/string.c
index 54fedc9..3e2de92 100644
--- a/src/libc/string.c
+++ b/src/libc/string.c
@@ -1,4 +1,4 @@
-int strlen(char* str)
+int strlen(const char* str)
 {
   int len = 0;
   while (*str++)
@@ -8,7 +8,7 @@ int strlen(char* str)
   return len;
 }
 
-int strcmp(char* str1, char* str2)
+int strcmp(const char* str1, const char* str2)
 {
   while (*str1 && (*str1 == *str2))
   {
@@ -16,4 +16,4 @@ int strcmp(char* str1, char* str2)
     str2++;
   }
   return *(const unsigned char*)str1 - *(const unsigned char*)str2;
-}
\ No newline at end of file
+}
diff --git a/src/libc/string.h b/src/libc/string.h
index 7e406bd..0f64804 100644
--- a/src/libc/string.h
+++ b/src/libc/string.h
@@ -1,7 +1,7 @@
 #ifndef INCLUDE_STRING_H
 #define INCLUDE_STRING_H
 
-int strlen(char* str);
-int strcmp(char* str1, char* str2);
+int strlen(const char* str);
+int strcmp(const char* str1, const char* str2);
 
 #endif
diff --git a/src/programs/misc.c b/src/programs/misc.c
index c255492..7b3c959 100644
--- a/src/programs/misc.c
+++ b/src/programs/misc.c
@@ -39,3 +39,15 @@ void program_uptime()
 	double seconds = ticks/18.2065; // PIC channel 0 freq
 	printf("%d ticks\t%f seconds\n", ticks, seconds);
 }
+
+// Get help
+
+void program_help()
+{
+	printf("help\tpanic\twords\tprimes\trainbow\tclear\nmath\tbf\tuptime\n");
+}
+
+void program_panic()
+{
+	asm volatile("int $0x13");
+}
diff --git a/src/programs/programs.h b/src/programs/programs.h
index c533b3b..568c570 100644
--- a/src/programs/programs.h
+++ b/src/programs/programs.h
@@ -10,5 +10,6 @@ void program_bf();
 void program_rainbow();
 void program_clear();
 void program_uptime();
-
+void program_panic();
+void program_help();
 #endif