diff --git a/hawk/lib/hawk-chr.h b/hawk/lib/hawk-chr.h
index 545e2844..eab266b6 100644
--- a/hawk/lib/hawk-chr.h
+++ b/hawk/lib/hawk-chr.h
@@ -91,6 +91,11 @@ typedef enum hawk_ooch_prop_t hawk_bch_prop_t;
 	 ((c) >= 'A' && (c) <= 'F')? ((c) - 'A' + 10): \
 	 ((c) >= 'a' && (c) <= 'f')? ((c) - 'a' + 10): -1)
 
+#define HAWK_ZDIGIT_TO_NUM(c,base) \
+	(((c) >= '0' && (c) <= '9')? ((c) - '0'): \
+	 ((c) >= 'A' && (c) <= 'Z')? ((c) - 'A' + 10): \
+	 ((c) >= 'a' && (c) <= 'z')? ((c) - 'a' + 10): base)
+
 #if defined(__cplusplus)
 extern "C" {
 #endif
diff --git a/hawk/lib/utl-str.c b/hawk/lib/utl-str.c
index 59189049..3b32f58f 100644
--- a/hawk/lib/utl-str.c
+++ b/hawk/lib/utl-str.c
@@ -2615,21 +2615,19 @@ hawk_int_t hawk_uchars_to_int (const hawk_uch_t* str, hawk_oow_t len, int option
 	} 
 	else if (rem >= 2 && base == 16)
 	{
-		if (*p == '0' && 
-		    (*(p + 1) == 'x' || *(p + 1) == 'X')) p += 2; 
+		if (*p == '0' && (*(p + 1) == 'x' || *(p + 1) == 'X')) p += 2; 
 	}
 	else if (rem >= 2 && base == 2)
 	{
-		if (*p == '0' && 
-		    (*(p + 1) == 'b' || *(p + 1) == 'B')) p += 2; 
+		if (*p == '0' && (*(p + 1) == 'b' || *(p + 1) == 'B')) p += 2; 
 	}
 
 	/* process the digits */
 	pp = p;
 	while (p < end)
 	{
-		digit = HAWK_XDIGIT_TO_NUM(*p);
-		if (digit <= - 1 || digit >= base) break;
+		digit = HAWK_ZDIGIT_TO_NUM(*p, base);
+		if (digit >= base) break;
 		n = n * base + digit;
 		p++;
 	}
@@ -2701,21 +2699,19 @@ hawk_int_t hawk_bchars_to_int (const hawk_bch_t* str, hawk_oow_t len, int option
 	} 
 	else if (rem >= 2 && base == 16)
 	{
-		if (*p == '0' && 
-		    (*(p + 1) == 'x' || *(p + 1) == 'X')) p += 2; 
+		if (*p == '0' && (*(p + 1) == 'x' || *(p + 1) == 'X')) p += 2; 
 	}
 	else if (rem >= 2 && base == 2)
 	{
-		if (*p == '0' && 
-		    (*(p + 1) == 'b' || *(p + 1) == 'B')) p += 2; 
+		if (*p == '0' && (*(p + 1) == 'b' || *(p + 1) == 'B')) p += 2; 
 	}
 
 	/* process the digits */
 	pp = p;
 	while (p < end)
 	{
-		digit = HAWK_XDIGIT_TO_NUM(*p);
-		if (digit <= - 1 || digit >= base) break;
+		digit = HAWK_ZDIGIT_TO_NUM(*p, base);
+		if (digit >= base) break;
 		n = n * base + digit;
 		p++;
 	}