diff --git a/lib/err.c b/lib/err.c
index c58ad00..3b526f5 100644
--- a/lib/err.c
+++ b/lib/err.c
@@ -83,6 +83,8 @@ static char* synerrstr[] =
 	"wrong character literal",
 	"invalid numeric literal",
 	"out of integer range",
+	"wrong error literal",
+	"wrong smptr literal",
 
 	"sudden end of input",
 	"( expected",
diff --git a/lib/hcl.h b/lib/hcl.h
index 5d6ca27..fe7be01 100644
--- a/lib/hcl.h
+++ b/lib/hcl.h
@@ -94,6 +94,8 @@ enum hcl_synerrnum_t
 	HCL_SYNERR_CHARLIT,       /* wrong character literal */
 	HCL_SYNERR_RADNUMLIT ,    /* invalid numeric literal with radix */
 	HCL_SYNERR_INTRANGE,      /* integer range error */
+	HCL_SYNERR_ERRORLIT,      /* wrong error literal */
+	HCL_SYNERR_SMPTRLIT,      /* wrong smptr literal */
 
 	HCL_SYNERR_EOF,           /* sudden end of input */
 	HCL_SYNERR_LPAREN,        /* ( expected */
@@ -236,38 +238,6 @@ typedef struct hcl_obj_word_t*     hcl_oop_word_t;
 #endif
 
 
-#if 0
-/* 
- * OOP encoding
- * An object pointer(OOP) is an ordinary pointer value to an object.
- * but some simple numeric values are also encoded into OOP using a simple
- * bit-shifting and masking.
- *
- * A real OOP is stored without any bit-shifting while a non-OOP value encoded
- * in an OOP is bit-shifted to the left by 2 and the 2 least-significant bits
- * are set to 1 or 2.
- * 
- * This scheme works because the object allocators aligns the object size to
- * a multiple of sizeof(hcl_oop_t). This way, the 2 least-significant bits
- * of a real OOP are always 0s.
- */
-
-#define HCL_OOP_TAG_BITS  2
-#define HCL_OOP_TAG_SMOOI 1
-#define HCL_OOP_TAG_CHAR  2
-
-#define HCL_OOP_IS_NUMERIC(oop) (((hcl_oow_t)oop) & (HCL_OOP_TAG_SMOOI | HCL_OOP_TAG_CHAR))
-#define HCL_OOP_IS_POINTER(oop) (!HCL_OOP_IS_NUMERIC(oop))
-#define HCL_OOP_GET_TAG(oop) (((hcl_oow_t)oop) & HCL_LBMASK(hcl_oow_t, HCL_OOP_TAG_BITS))
-
-#define HCL_OOP_IS_SMOOI(oop) (((hcl_ooi_t)oop) & HCL_OOP_TAG_SMOOI)
-#define HCL_OOP_IS_CHAR(oop) (((hcl_oow_t)oop) & HCL_OOP_TAG_CHAR)
-#define HCL_SMOOI_TO_OOP(num) ((hcl_oop_t)((((hcl_ooi_t)(num)) << HCL_OOP_TAG_BITS) | HCL_OOP_TAG_SMOOI))
-#define HCL_OOP_TO_SMOOI(oop) (((hcl_ooi_t)oop) >> HCL_OOP_TAG_BITS)
-#define HCL_CHAR_TO_OOP(num) ((hcl_oop_t)((((hcl_oow_t)(num)) << HCL_OOP_TAG_BITS) | HCL_OOP_TAG_CHAR))
-#define HCL_OOP_TO_CHAR(oop) (((hcl_oow_t)oop) >> HCL_OOP_TAG_BITS)
-
-#else
 /* 
  * OOP encoding
  * An object pointer(OOP) is an ordinary pointer value to an object.
@@ -327,8 +297,6 @@ typedef struct hcl_obj_word_t*     hcl_oop_word_t;
 #define HCL_OOP_TO_ERROR(oop) (((hcl_oow_t)oop) >> (HCL_OOP_TAG_BITS_LO + HCL_OOP_TAG_BITS_LO))
 #define HCL_ERROR_TO_OOP(num) ((hcl_oop_t)((((hcl_oow_t)(num)) << (HCL_OOP_TAG_BITS_LO + HCL_OOP_TAG_BITS_LO)) | HCL_OOP_TAG_ERROR))
 
-#endif
-
 /* SMOOI takes up 62 bit on a 64-bit architecture and 30 bits 
  * on a 32-bit architecture. The absolute value takes up 61 bits and 29 bits
  * respectively for the 1 sign bit. */
@@ -341,6 +309,21 @@ typedef struct hcl_obj_word_t*     hcl_oop_word_t;
 #define HCL_SMOOI_MIN (-HCL_SMOOI_MAX)
 #define HCL_IN_SMOOI_RANGE(ooi)  ((ooi) >= HCL_SMOOI_MIN && (ooi) <= HCL_SMOOI_MAX)
 
+
+/* SMPTR is a special value which has been devised to encode an address value
+ * whose low HCL_OOP_TAG_BITS_LO bits are 0. its class is SmallPointer. A pointer
+ * returned by most of system functions would be aligned to the pointer size. 
+ * you can use the followings macros when converting such a pointer without loss. */
+#define HCL_IN_SMPTR_RANGE(ptr) ((((hcl_oow_t)ptr) & HCL_LBMASK(hcl_oow_t, HCL_OOP_TAG_BITS_LO)) == 0)
+
+#define HCL_CHAR_BITS (HCL_OOI_BITS - HCL_OOP_TAG_BITS_LO - HCL_OOP_TAG_BITS_HI)
+#define HCL_CHAR_MIN 0
+#define HCL_CHAR_MAX (~((hcl_oow_t)0) >> (HCL_OOP_TAG_BITS_LO + HCL_OOP_TAG_BITS_HI))
+
+#define HCL_ERROR_BITS (HCL_OOI_BITS - HCL_OOP_TAG_BITS_LO - HCL_OOP_TAG_BITS_HI)
+#define HCL_ERROR_MIN 0
+#define HCL_ERROR_MAX (~((hcl_oow_t)0) >> (HCL_OOP_TAG_BITS_LO + HCL_OOP_TAG_BITS_HI))
+
 /* TODO: There are untested code where smint is converted to hcl_oow_t.
  *       for example, the spec making macro treats the number as hcl_oow_t instead of hcl_ooi_t.
  *       as of this writing, i skip testing that part with the spec value exceeding HCL_SMOOI_MAX.
diff --git a/lib/print.c b/lib/print.c
index 35fca77..2a32a84 100644
--- a/lib/print.c
+++ b/lib/print.c
@@ -191,7 +191,7 @@ next:
 	}
 	else if (HCL_OOP_IS_SMPTR(obj))
 	{
-		if (outbfmt(hcl, mask, "#\\p%zu", (hcl_oow_t)HCL_OOP_TO_SMPTR(obj)) <= -1) return -1;
+		if (outbfmt(hcl, mask, "#\\p%zX", (hcl_oow_t)HCL_OOP_TO_SMPTR(obj)) <= -1) return -1;
 		goto done;
 	}
 	else if (HCL_OOP_IS_ERROR(obj))
diff --git a/lib/read.c b/lib/read.c
index 5ad71ef..d55c4d0 100644
--- a/lib/read.c
+++ b/lib/read.c
@@ -823,12 +823,13 @@ static int get_sharp_token (hcl_t* hcl)
 
 			if (TOKEN_NAME_LEN(hcl) >= 4)
 			{
-				if (hcl->c->tok.name.ptr[2] == 'p')
+				if (TOKEN_NAME_CHAR(hcl, 2) == 'P' || TOKEN_NAME_CHAR(hcl, 2) == 'p')
 				{
 					SET_TOKEN_TYPE (hcl, HCL_IOTOK_SMPTRLIT);
 					goto hexcharlit;
 				}
-				else if (hcl->c->tok.name.ptr[2] == 'x' || hcl->c->tok.name.ptr[2] == 'u')
+				else if (TOKEN_NAME_CHAR(hcl, 2) == 'X' || TOKEN_NAME_CHAR(hcl, 2) == 'x' ||
+				         TOKEN_NAME_CHAR(hcl, 2) == 'U' || TOKEN_NAME_CHAR(hcl, 2) == 'u')
 				{
 					hcl_oow_t i;
 
@@ -845,7 +846,7 @@ static int get_sharp_token (hcl_t* hcl)
 						c = c * 16 + CHAR_TO_NUM(hcl->c->tok.name.ptr[i], 16); /* don't care if it is for 'p' */
 					}
 				}
-				else if (hcl->c->tok.name.ptr[2] == 'e')
+				else if (TOKEN_NAME_CHAR(hcl, 2) == 'E' || TOKEN_NAME_CHAR(hcl, 2) == 'e')
 				{
 					hcl_oow_t i;
 					for (i = 3; i < TOKEN_NAME_LEN(hcl); i++)
@@ -1756,7 +1757,6 @@ static int read_object (hcl_t* hcl)
 		switch (TOKEN_TYPE(hcl)) 
 		{
 			default:
-				HCL_ASSERT (hcl, !"should never happen - invalid token type");
 				hcl_seterrbfmt (hcl, HCL_EINTERN, "invalid token encountered - %d %.*js", 
 					TOKEN_TYPE(hcl), TOKEN_NAME_LEN(hcl), TOKEN_NAME_PTR(hcl));
 				return -1;
@@ -1960,6 +1960,13 @@ static int read_object (hcl_t* hcl)
 					v = v * 16 + CHAR_TO_NUM(TOKEN_NAME_CHAR(hcl, i), 16);
 				}
 
+				if (!HCL_IN_SMPTR_RANGE(v))
+				{
+					hcl_setsynerr (hcl, HCL_SYNERR_SMPTRLIT, TOKEN_LOC(hcl), TOKEN_NAME(hcl));
+					return -1;
+				}
+
+
 				obj = HCL_SMPTR_TO_OOP(v);
 				break;
 			}
@@ -1974,6 +1981,12 @@ static int read_object (hcl_t* hcl)
 				{
 					HCL_ASSERT (hcl, is_digitchar(TOKEN_NAME_CHAR(hcl, i)));
 					v = v * 10 + CHAR_TO_NUM(TOKEN_NAME_CHAR(hcl, i), 10);
+
+					if (v > HCL_ERROR_MAX)
+					{
+						hcl_setsynerr (hcl, HCL_SYNERR_ERRORLIT, TOKEN_LOC(hcl), TOKEN_NAME(hcl));
+						return -1;
+					}
 				}
 
 				obj = HCL_ERROR_TO_OOP(v);