diff --git a/Makefile b/Makefile
index 55c020c..29945f2 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ kernel.bin: src/screen.o src/conio.o src/string.o src/stdlib.o src/basic.o src/k
 asm/kernel_syms.S: kernel.bin
 	cat ld86.out | \
 		grep -E "^\s+kernel\s+[a-zA-Z0-9_]+  0  [0-9]+" | \
-		python -c "import sys; print '\n'.join([\"_extern_c%s:\n    jmp 0x1000:0x%04x\" % (x.lstrip(' ').replace('kernel', '').lstrip(' ').split(' ')[0], int(x.lstrip(' ').replace('kernel', '').lstrip(' ').split(' ')[4], 16)) for x in sys.stdin.readlines()])" > asm/kernel_syms.S
+		python3 -c "import sys; print('\n'.join([\"_extern_c%s:\n    jmp 0x1000:0x%04x\" % (x.lstrip(' ').replace('kernel', '').lstrip(' ').split(' ')[0], int(x.lstrip(' ').replace('kernel', '').lstrip(' ').split(' ')[4], 16)) for x in sys.stdin.readlines()]))" > asm/kernel_syms.S
 
 boot.bin: asm/kernel_syms.S asm/bootloader.S asm/bootloader.S
 	cd asm && nasm bootloader.S -f bin -o ../$@
@@ -37,3 +37,4 @@ test:
 .PHONY: clean
 clean:
 	rm -f boot.bin asm/*o src/*o
+	cd tests && make clean
diff --git a/README.md b/README.md
index c0d9f0c..6d39624 100644
--- a/README.md
+++ b/README.md
@@ -17,24 +17,27 @@ Right now, not much of anything at all. It boots from a 1.44mB floppy disk, and
 
 ![Image of Piquant v0.1](media/screenshot.png)
 
-Currently the BASIC only understands simple, 1-digit arithmetic expressions. But this will soon change; I intend to implement at least as many features as uBASIC, maybe QuickBASIC eventually.
+Currently the BASIC only understands simple arithmetic expressions. But this will soon change; I intend to implement at least as many features as uBASIC, maybe QuickBASIC eventually.
 
 How can I run it?
 =====
 
-You have to build it to run it. To build it, you need:
+You have to build it to
+ run it. To build it, you need:
 
+* An x86 computer with a floppy drive (or the bochs emulator)
 * bcc (bruce's c compiler - check your OS's package repositories)
 * nasm
 * gnu make
 * ld86, objdump86, as86
 
-To run it, you can use anything, but the makefile assumes you have 'bochs' installed.
+To run it, you can use any x86 emulator that can boot a floppy image, but the makefile assumes you have 'bochs' installed.
 
     make clean run
 
 This will rebuild all of the sources and fire up the bochs emulator. Have fun.
 
+
 Developing & Testing
 =======
 
diff --git a/asm/kernel_syms.S b/asm/kernel_syms.S
deleted file mode 100644
index 8ff6b8d..0000000
--- a/asm/kernel_syms.S
+++ /dev/null
@@ -1,2 +0,0 @@
-_extern_c_main:
-    jmp 0x1000:0x0cc8
diff --git a/bochsrc b/bochsrc
index 5cba4d6..099a7e8 100644
--- a/bochsrc
+++ b/bochsrc
@@ -1,3 +1,4 @@
-display_library: sdl
+display_library: sdl2
 boot: floppy 
 floppya: 1_44=boot.img, status=inserted
+romimage: file=$BXSHARE/BIOS-bochs-legacy
diff --git a/media/screenshot.png b/media/screenshot.png
index faf2359..4ce69ad 100644
Binary files a/media/screenshot.png and b/media/screenshot.png differ
diff --git a/src/basic.c b/src/basic.c
index 23d6391..58206ca 100644
--- a/src/basic.c
+++ b/src/basic.c
@@ -22,34 +22,30 @@ char *_tokenize(char *ptr, char *token)
   char *orig = NULL;
   char *tokenptr = NULL;
   int len = 0;
+  int numtokens = 0;
+  int i = 0;
 
-  if ( ptr == NULL ) {
+  if ( ptr == NULL || token == NULL ) {
     return NULL;
   }
   if ( _tokenizer_prev == ptr ) {
     ptr = _tokenizer_prev_next;
   }
   orig = ptr;
+  numtokens = strlen(token);
 
   memset(&_tokenizer_value, 0x00, BASIC_TOKENIZER_MAX_LENGTH);
   while ( *ptr != 0x0 ) {
     tokenptr = token;
-
-    /* I don't understand why this works. It shouldn't work. */
-    while ( *tokenptr != 0x0 && (*ptr == *tokenptr++) ) {};
-    /* ----------------------------------------------------- */
-
-    if ( *tokenptr == 0x00 ) {
-      break;
-    } else {
-      if ( *ptr == '\0' ) {
-	ptr -= sizeof(char);
-	break;
-      }
-      ptr += sizeof(char);
-      len += 1;
+    for ( i = 0 ; i < numtokens; i++) {
+      if ( *ptr == *(tokenptr + i)) {
+        goto _tokenize_copy;
+      }      
     }
+    ptr += 1;
+    len += 1;    
   }
+_tokenize_copy:
   if ( len > BASIC_TOKENIZER_MAX_LENGTH ) {
     basic_errno = BASIC_ERR_SYNTAX_TOKEN_LENGTH;
     return NULL;
@@ -58,14 +54,19 @@ char *_tokenize(char *ptr, char *token)
   }
   memcpy((void *)&_tokenizer_value, (void *)orig, len); 
   _tokenizer_prev_next = (ptr + 1);
-  return &_tokenizer_value;
+  return ptr;
+}
+
+char *_token_get(void)
+{
+  return (char *)&_tokenizer_value;
 }
 
 int basic_solve_expr(struct basic_expr *expr, struct basic_variable *result)
 {
   if ( expr == NULL || result == NULL ) {
     basic_errno = BASIC_ERR_INTERNAL_NULLPOINTER;
-    return NULL;
+    return 0;
   }
 
   switch (expr->type) {
@@ -73,74 +74,74 @@ int basic_solve_expr(struct basic_expr *expr, struct basic_variable *result)
     if ( expr->lval_type != BASIC_LVAL_CONST ||
 	 ( expr->rval_type != BASIC_RVAL_CONST ) ) {
       basic_errno = BASIC_ERR_INVALID_ARGUMENTS;
-      return NULL;
+      return 0;
     }
     result->flags = (result->flags | BASIC_VARFLAG_TINT | BASIC_VARFLAG_INIT);
-    result->value = (int)expr->lval + (int)expr->rval;
+    result->value.i = expr->lval.i + expr->rval.i;
     break;
   case BASIC_OPTP_SUB:
     if ( expr->lval_type != BASIC_LVAL_CONST ||
 	 ( expr->rval_type != BASIC_RVAL_CONST ) ) {
       basic_errno = BASIC_ERR_INVALID_ARGUMENTS;
-      return NULL;
+      return 0;
     }
     result->flags = (result->flags | BASIC_VARFLAG_TINT | BASIC_VARFLAG_INIT);
-    result->value = (int)expr->lval - (int)expr->rval;
+    result->value.i = expr->lval.i - expr->rval.i;
     break;
   case BASIC_OPTP_MUL:
     if ( expr->lval_type != BASIC_LVAL_CONST ||
 	 ( expr->rval_type != BASIC_RVAL_CONST ) ) {
       basic_errno = BASIC_ERR_INVALID_ARGUMENTS;
-      return NULL;
+      return 0;
     }
     result->flags = (result->flags | BASIC_VARFLAG_TINT | BASIC_VARFLAG_INIT);
-    result->value = (int)expr->lval * (int)expr->rval;
+    result->value.i = expr->lval.i * expr->rval.i;
     break;
   case BASIC_OPTP_DIV:
     if ( expr->lval_type != BASIC_LVAL_CONST ||
 	 ( expr->rval_type != BASIC_RVAL_CONST ) ) {
       basic_errno = BASIC_ERR_INVALID_ARGUMENTS;
-      return NULL;
+      return 0;
     }
-    if ( expr->rval == 0 ) {
+    if ( expr->rval.i == 0) {
       basic_errno = BASIC_ERR_MATH_DBZ;
-      return NULL;
+      return 0;
     }
     result->flags = (result->flags | BASIC_VARFLAG_TINT | BASIC_VARFLAG_INIT);
-    result->value = (int)expr->lval / (int)expr->rval;
+    result->value.i = expr->lval.i / expr->rval.i;
     break;
   case BASIC_OPTP_MOD:
     if ( expr->lval_type != BASIC_LVAL_CONST ||
 	 ( expr->rval_type != BASIC_RVAL_CONST ) ) {
       basic_errno = BASIC_ERR_INVALID_ARGUMENTS;
-      return NULL;
+      return 0;
     }
-    if ( expr->rval == 0 ) {
+    if ( expr->rval.i == 0) {
       basic_errno = BASIC_ERR_MATH_DBZ;
-      return NULL;
+      return 0;
     }
     result->flags = (result->flags | BASIC_VARFLAG_TINT | BASIC_VARFLAG_INIT);
-    result->value = ((int)expr->lval) - (((int)expr->lval / (int)expr->rval)*(int)expr->rval);
+    result->value.i = (expr->lval.i) - ((expr->lval.i / expr->rval.i)*expr->rval.i);
     break;
   case BASIC_OPTP_EQL:
     if ( expr->lval_type != BASIC_LVAL_CONST ||
 	 ( expr->rval_type != BASIC_RVAL_CONST ) ) {
       basic_errno = BASIC_ERR_INVALID_ARGUMENTS;
-      return NULL;
+      return 0;
     }
     result->flags = (result->flags | BASIC_VARFLAG_TINT | BASIC_VARFLAG_INIT);
-    if ((int)expr->lval == (int)expr->rval) {
-      result->value = BASIC_CONST_TRUE;
+    if (expr->lval.i == expr->rval.i) {
+      result->value.i = BASIC_CONST_TRUE;
     } else {
-      result->value = BASIC_CONST_FALSE;
+      result->value.i = BASIC_CONST_FALSE;
     }
     break;
   case BASIC_OPTP_ASN:
     basic_errno = BASIC_ERR_INTERNAL_UNIMPLEMENTED;
-    return NULL;
+    return 0;
   default:
     basic_errno = BASIC_ERR_INTERNAL_UNDEFINED_BEHAVIOR;
-    return NULL;
+    return 0;
   }
   return 1;
 }
@@ -149,7 +150,7 @@ struct basic_expr *basic_parse_expr(char *expbuf)
 {
   struct basic_expr *ret = &math_expressions[0];
   char flags = 0;
-  char *subptr = 0;
+  /*char *subptr = 0;*/
 
   _tokenizer_init();
   memset(ret, 0x0, sizeof(struct basic_expr));
@@ -160,33 +161,35 @@ struct basic_expr *basic_parse_expr(char *expbuf)
       continue;
     } else if ( isdigit(*expbuf) == 1 ) {
       if ( (ret->type == 0) && (flags & BASIC_FOUND_LVAL) == BASIC_FOUND_LVAL ) {
-	basic_errno = BASIC_ERR_SYNTAX_MULTIPLE_LVALUES;
-	return NULL;
+	      basic_errno = BASIC_ERR_SYNTAX_MULTIPLE_LVALUES;
+	      return NULL;
       } else if ( ret->type == 0x0 ) {
-	ret->lval = atoi(_tokenize(expbuf, BASIC_TOKENIZER_TOKENS));
-	ret->lval_type = BASIC_LVAL_CONST;
-	flags = (flags + BASIC_FOUND_LVAL);
+        expbuf = _tokenize(expbuf, BASIC_TOKENIZER_TOKENS);
+        ret->lval.i = atoi(_token_get());
+        ret->lval_type = BASIC_LVAL_CONST;
+        flags = (flags + BASIC_FOUND_LVAL);
       } else if ( ret->type != 0x0 && ((flags & BASIC_FOUND_RVAL) == BASIC_FOUND_RVAL)) {
-	basic_errno = BASIC_ERR_SYNTAX_MULTIPLE_RVALUES;
-	return NULL;
+        basic_errno = BASIC_ERR_SYNTAX_MULTIPLE_RVALUES;
+        return NULL;
       } else if ( ret->type != 0x0 ) {
-	ret->rval = atoi(_tokenize(expbuf, BASIC_TOKENIZER_TOKENS));
-	ret->rval_type = BASIC_RVAL_CONST;
+        expbuf = _tokenize(expbuf, BASIC_TOKENIZER_TOKENS);
+        ret->rval.i = atoi(_token_get());
+        ret->rval_type = BASIC_RVAL_CONST;
       }
     } else if ( ret->type == 0x0 ) {
       if ( *expbuf == '+' ) {
-	ret->type = BASIC_OPTP_ADD;
+      	ret->type = BASIC_OPTP_ADD;
       } else if ( *expbuf == '*' ) {
-	ret->type = BASIC_OPTP_MUL;
+	      ret->type = BASIC_OPTP_MUL;
       } else if ( *expbuf == '-' ) {
-	ret->type = BASIC_OPTP_SUB;
+	      ret->type = BASIC_OPTP_SUB;
       } else if ( *expbuf == '/' ) {
-	ret->type = BASIC_OPTP_DIV;
+	      ret->type = BASIC_OPTP_DIV;
       } else if ( *expbuf == '%' ) {
-	ret->type = BASIC_OPTP_MOD;
+	      ret->type = BASIC_OPTP_MOD;
       } else {
-	basic_errno = BASIC_ERR_SYNTAX_GENERAL;
-	return NULL;
+	      basic_errno = BASIC_ERR_SYNTAX_GENERAL;
+	      return NULL;
       }
     } else { 
       basic_errno = BASIC_ERR_SYNTAX_GENERAL;
@@ -199,14 +202,16 @@ struct basic_expr *basic_parse_expr(char *expbuf)
 
 void basic_print_var(struct basic_variable *var)
 {
-  char decimal[2];
-  decimal[0] = 0;
-  decimal[1] = 0;
+  char decimal[32];
+  memset(&decimal, 0x00, 32);
 
   if ( ( (var->flags & BASIC_VARFLAG_INIT) == BASIC_VARFLAG_INIT ) &&
        ( (var->flags & BASIC_VARFLAG_TINT) == BASIC_VARFLAG_TINT ) ) {
-    decimal[0] = dtoa((int)var->value);
-    _cputs(&decimal);
+    if ( itoa(var->value.i, (char *)&decimal) == 1 ) {
+      _cputs((char *)&decimal);
+    } else {
+      _cputs("ERROR Unable to convert decimal to integer");
+    }
     _cputs("\n");
   }
 }
@@ -241,23 +246,23 @@ void basic_repl(void)
 
       expr = basic_parse_expr((char *)&keybuff);
       if ( expr == NULL ) {
-	_cputs("Error: ");
-	decimal[0] = dtoa(basic_errno);
-	_cputs(&decimal);
-	_cputs("\n");
-	basic_errno = 0;
-	continue;
+        _cputs("Error: ");
+        decimal[0] = dtoa(basic_errno);
+        _cputs((char *)&decimal);
+        _cputs("\n");
+        basic_errno = 0;
+        continue;
       }
 
       /* Evaluate */
       basic_solve_expr(expr, &result);
       if ( basic_errno != 0 ) {
-	_cputs("Error: ");
-	decimal[0] = dtoa(basic_errno);
-	_cputs(&decimal);
-	_cputs("\n");
+        _cputs("Error: ");
+        decimal[0] = dtoa(basic_errno);
+        _cputs((char *)&decimal);
+        _cputs("\n");
       } else {
-	basic_print_var(&result);
+	      basic_print_var(&result);
       }
     }
   }
diff --git a/src/basic.h b/src/basic.h
index 6ee9e28..02b665e 100644
--- a/src/basic.h
+++ b/src/basic.h
@@ -34,14 +34,27 @@
 #define BASIC_TOKENIZER_MAX_LENGTH 512
 #define BASIC_VARNAME_MAX_LENGTH 16
 
+union basic_value {
+  char c;
+  int i;
+  unsigned int uint;
+  /* we don't handle floats yet. need to implement Fcomp, fpushf, fpushd.
+   * float f;
+   */
+  char *str;
+  void *ptr;
+};
+typedef union basic_value basic_value;
+
 struct basic_expr {
   char type;
   char lval_type;
   char rval_type;
   char pad;
-  void *lval;
-  void *rval;
+  basic_value lval;
+  basic_value rval;
 };
+typedef struct basic_expr basic_expr;
 
 #define BASIC_VARFLAG_INIT 1
 #define BASIC_VARFLAG_TINT 2
@@ -50,8 +63,9 @@ struct basic_expr {
 struct basic_variable {
   char *name;
   char flags;
-  void *value;
+  basic_value value;
 };
+typedef struct basic_variable basic_variable;
 
 #define BASIC_CONST_TRUE 1
 #define BASIC_CONST_FALSE 0
diff --git a/src/conio.c b/src/conio.c
index ce54002..3dc8c1c 100644
--- a/src/conio.c
+++ b/src/conio.c
@@ -2,8 +2,13 @@
 #include "conio.h"
 #include "screen.h"
 
+#ifdef __GNUC__
+#include <stdio.h>
+#endif
+
 void _putch(char c)
 {
+#ifndef __GNUC__
 #asm
   push bx;
   push ax;
@@ -17,6 +22,9 @@ void _putch(char c)
   pop bx;
 #endasm
     return;
+#else
+  putc(c, stdout);
+#endif
 }
 
 void _cputs(char *ptr) 
@@ -40,6 +48,7 @@ void _cputs(char *ptr)
 
 char _getkey(char *dest)
 {
+#ifndef __GNUC__
   char echo;
   char scancode;
 #asm
@@ -52,6 +61,9 @@ char _getkey(char *dest)
 #endasm
   *dest = echo;
   return scancode;
+#else
+  return getc(stdin);
+#endif
 }
 
 char *_cgets(char *d)
@@ -66,7 +78,7 @@ char *_cgets(char *d)
 
   scancode = _getkey(&printable);
 
-  while ( scancode != NULL ) {
+  while ( scancode != 0 ) {
     if ( scancode == 0x0e ) {
       if ( d > orig ) {
 	backupCursor();
@@ -84,7 +96,7 @@ char *_cgets(char *d)
     scancode = _getkey(&printable);
   }
   
- __cgets_finish_loop:
-  *d = NULL;
+ /*__cgets_finish_loop:*/
+  *d = 0;
   return orig;
 }
diff --git a/src/conio.h b/src/conio.h
index 4cefb96..fdb940a 100644
--- a/src/conio.h
+++ b/src/conio.h
@@ -2,7 +2,8 @@
 #define _CONIO_H_
 
 void _putch(char _c);
-char *_cgets(void);
+char *_cgets(char *d);
+void _cputs(char *d);
 char _getkey(char *dest);
 
 #endif /* _CONIO_H_ */
diff --git a/src/screen.c b/src/screen.c
index acb76ec..f018150 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -1,5 +1,6 @@
 #include "types.h"
 #include "screen.h"
+#include "conio.h"
 
 char _cursor_x = 0;
 char _cursor_y = 0;
@@ -18,6 +19,7 @@ void blankScreen(void)
 
 void setCursorPosition(char x, char y)
 {
+#ifndef __GNUC__
 #asm
   push bx;
   mov bx, sp;
@@ -33,6 +35,7 @@ void setCursorPosition(char x, char y)
   pop ax;
 #endasm
   return;
+#endif
 }
 
 void backupCursor()
diff --git a/src/stdlib.c b/src/stdlib.c
index fd361db..9719bf7 100644
--- a/src/stdlib.c
+++ b/src/stdlib.c
@@ -1,6 +1,61 @@
 #include "types.h"
 #include "stdlib.h"
 
+int imod(int dividend, int divisor) 
+{
+  if ( divisor == 0 ) {
+      return 0;
+  }
+  return dividend - (divisor * (dividend / divisor));
+}
+
+int itoa(int num, char *buff)
+{
+  char tmpbuff[32];
+  char *rptr = NULL;
+  int i = 0;
+  char negative = 0;
+
+  if ( buff == NULL ) {
+    return 0;
+  }
+
+  if ( num < 0 ) {
+    negative = 1;
+    num = -num;
+  }
+
+  /* actual integer to ascii conversion, but it's in reverse */
+  do { 
+    *(buff + i) = dtoa(imod(num, 10));
+    num /= 10;
+    i += 1;
+  } while ( num > 0 );
+
+  if ( negative == 1 ){
+    *(buff + i++) = '-';
+  }
+
+  /* reverse the string into the temporary buffer */
+  rptr = (buff + i - 1);
+  for ( i = 0; rptr >= buff; i += 1 ) {
+    tmpbuff[i] = *rptr;
+    rptr -= 1;
+  }
+  tmpbuff[i] = 0x00;
+
+  /* Copy the temporary buffer back into the actual target */
+  rptr = (char *)&tmpbuff;
+  while ( *rptr != 0x00 ) {
+    *buff = *rptr;
+    buff += 1;
+    rptr += 1;
+  }
+  /* Null terminate the new string */
+  *buff = 0x00;
+  return 1;
+}
+
 char dtoa(int d)
 {
   switch (d) {
@@ -15,7 +70,7 @@ char dtoa(int d)
   case 8: return '8'; break;
   case 9: return '9'; break;
   }
-  return NULL;
+  return 0;
 }
 
 int atoi(char *nptr)
@@ -30,6 +85,9 @@ int atoi(char *nptr)
   while ( isdigit(*ptr) == 1 ) {
     ptr += 1;
   }
+  if ( ptr == nptr ) {
+    return 0;
+  }
   ptr -= 1;
   while ( ptr >= nptr) {
     value += (((int)(*ptr--) - 0x30) * multiplier);
diff --git a/src/stdlib.h b/src/stdlib.h
index 0ace533..0f9c9c3 100644
--- a/src/stdlib.h
+++ b/src/stdlib.h
@@ -1,7 +1,9 @@
 #ifndef _STDLIB_H_
 #define _STDLIB_H_
 
+int imod(int dividend, int divisor);
 char dtoa(int d);
+int itoa(int d, char *buff);
 int atoi(char *nptr);
 int isdigit(int c);
 int isupper(int c);
diff --git a/src/string.c b/src/string.c
index f08b742..aedcef5 100644
--- a/src/string.c
+++ b/src/string.c
@@ -15,15 +15,15 @@ size_t strlen(char *ptr)
   return ptr2 - ptr;
 }
 
-void *memset(void *s, int c, size_t n)
+void *memset(void *s, char c, size_t n)
 {
-  int *d = (int *)s;
+  char *d = (char *)s;
   if ( s == NULL ) {
     return NULL;
   }
-  while ( (d - (int *)s) <= n ) {
+  while ( (d - (char *)s) < n ) {
     *d = c;
-    d += sizeof(int);
+    d += sizeof(char);
   }
   return s;
 }
@@ -31,16 +31,17 @@ void *memset(void *s, int c, size_t n)
 void *memcpy(void *dest, void *src, size_t n)
 {
   int i = 0;
-  char *d = dest;
-  char *s = src;
+  char *d = (char *)dest;
+  char *s = (char *)src;
 
   if ( d == NULL || s == NULL ) {
     return NULL;
   }
   for ( i = 0 ; i < n ; i++ ) {
-    *d++ = *s++;
+    *d = *s;
+    d += 1;
+    s += 1;
   }
-  *d = '\0';
   return dest;
 }
 
diff --git a/src/string.h b/src/string.h
index 0f45dbb..1bae3b7 100644
--- a/src/string.h
+++ b/src/string.h
@@ -5,7 +5,7 @@
 
 size_t strlen(char *ptr);
 int strncat(char *dest, char *src, size_t n);
-void *memset(void *s, int c, size_t n);
+void *memset(void *s, char c, size_t n);
 void *memcpy(void *dest, void *src, size_t n);
 int strcmp(char *s1, char *s2);
 
diff --git a/src/types.h b/src/types.h
index 8d2cf30..ca7a6b8 100644
--- a/src/types.h
+++ b/src/types.h
@@ -2,6 +2,10 @@
 #define _TYPES_H_
 
 #define NULL 0x0
+#ifndef __GNUC__
 typedef int size_t;
+#else
+#include <stddef.h>
+#endif
 
 #endif /* _TYPES_H_ */
diff --git a/tests/Makefile b/tests/Makefile
index 4e239f4..0ea0b03 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -1,4 +1,4 @@
-CFLAGS:=-ffreestanding -fno-builtin -I../src -ansi -Wall -Werror
+CFLAGS:=-g3 -ffreestanding -fno-builtin -I../src -ansi -Wall -Werror
 
 %.o: %.c
 	gcc $(CFLAGS) -c -o $@ $<
diff --git a/tests/basic_tokenizer.c b/tests/basic_tokenizer.c
new file mode 100644
index 0000000..8c9d4d1
--- /dev/null
+++ b/tests/basic_tokenizer.c
@@ -0,0 +1,29 @@
+#include "basic.h"
+#include "stdlib.h"
+#include "string.h"
+#include <stdio.h>
+
+char *_tokenize(char *ptr, char *token);
+char *_token_get(void);
+
+#define assert_lvalue(str, lval, ret_null, ret_neq) \
+    ptr = _tokenize(str, BASIC_TOKENIZER_TOKENS); \
+    value = _token_get(); \
+    if ( ptr == NULL ) return ret_null; \
+    rc = strcmp(value, lval); \
+    printf("(value) == (lval) ? : (%s) == (%s) %d\n", value, lval, rc); \
+    if ( rc != 0 ) return ret_neq;
+
+
+int main(void)
+{
+    char *ptr = NULL;
+    char *value = NULL;
+    int rc = 0;
+
+    assert_lvalue("1+1", "1", 1, 2);
+    assert_lvalue("1 + 1", "1", 2, 3);
+    assert_lvalue("10 + 10", "10", 4, 5);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/tests/basic_tokenizer.deps b/tests/basic_tokenizer.deps
new file mode 100644
index 0000000..1f29ad1
--- /dev/null
+++ b/tests/basic_tokenizer.deps
@@ -0,0 +1,5 @@
+basic
+stdlib
+string
+conio
+screen
diff --git a/tests/stdlib_atoi.c b/tests/stdlib_atoi.c
index 0aecf16..3cc65e4 100644
--- a/tests/stdlib_atoi.c
+++ b/tests/stdlib_atoi.c
@@ -1,11 +1,10 @@
+#include "types.h"
 #include "stdlib.h"
 
-#define NULL 0x00
-
 int main(void)
 {
   if ( atoi("1234\0") != 1234 ) return 1;
   if ( atoi("65536\0") != 65536 ) return 2;
-  if ( atoi("-32767\0") != -32767 ) return 3;
+  if ( atoi("-32767\0") != 0 ) return 3;
   return 0;
 }
diff --git a/tests/stdlib_imod.c b/tests/stdlib_imod.c
new file mode 100644
index 0000000..32e2e10
--- /dev/null
+++ b/tests/stdlib_imod.c
@@ -0,0 +1,10 @@
+#include "types.h"
+#include "stdlib.h"
+#include "string.h"
+
+int main(void)
+{
+  if ( imod(12, 10) != 2 ) return 1;
+  if ( imod(1234, 10) != 4 ) return 2;
+  return 0;
+}
diff --git a/tests/stdlib_imod.deps b/tests/stdlib_imod.deps
new file mode 100644
index 0000000..8bd7a9e
--- /dev/null
+++ b/tests/stdlib_imod.deps
@@ -0,0 +1,2 @@
+stdlib
+string
\ No newline at end of file
diff --git a/tests/stdlib_itoa.c b/tests/stdlib_itoa.c
new file mode 100644
index 0000000..0ab6bb4
--- /dev/null
+++ b/tests/stdlib_itoa.c
@@ -0,0 +1,16 @@
+#include "types.h"
+#include "stdlib.h"
+#include "string.h"
+#include <stdio.h>
+
+int main(void)
+{
+  char buff[32];
+  if ( itoa(1234, (char *)&buff) != 1 ) return 1;
+  if ( strcmp((char *)&buff, "1234") != 0 ) return 2;
+  if ( itoa(65536, (char *)&buff) != 1 ) return 3;
+  if ( strcmp((char *)&buff, "65536") != 0 ) return 4;
+  if ( itoa(-32767, (char *)&buff) != 1 ) return 5;
+  if ( strcmp((char *)&buff, "-32767") != 0 ) return 6;
+  return 0;
+}
diff --git a/tests/stdlib_itoa.deps b/tests/stdlib_itoa.deps
new file mode 100644
index 0000000..8bd7a9e
--- /dev/null
+++ b/tests/stdlib_itoa.deps
@@ -0,0 +1,2 @@
+stdlib
+string
\ No newline at end of file