diff --git a/hawk/lib/tre-ast.c b/hawk/lib/tre-ast.c
index a95de245..e8b6d526 100644
--- a/hawk/lib/tre-ast.c
+++ b/hawk/lib/tre-ast.c
@@ -220,7 +220,7 @@ tre_do_print(FILE *stream, tre_ast_node_t *ast, int indent)
 		else
 		{
 			fprintf(stream, "literal (%c, %c) (%d, %d), pos %d, sub %d, "
-			        "%d tags\n", code_min, code_max, code_min, code_max, pos,
+			        "%d tags\n", (int)code_min, (int)code_max, (int)code_min, (int)code_max, pos,
 			        ast->submatch_id, num_tags);
 		}
 		break;
diff --git a/hawk/lib/tre-ast.h b/hawk/lib/tre-ast.h
index 4e0f1bb0..f89090bc 100644
--- a/hawk/lib/tre-ast.h
+++ b/hawk/lib/tre-ast.h
@@ -59,8 +59,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 
-#ifndef _HAWK_LIB_CMN_TRE_AST_H_
-#define _HAWK_LIB_CMN_TRE_AST_H_
+#ifndef _HAWK_LIB_TRE_AST_H_
+#define _HAWK_LIB_TRE_AST_H_
 
 #include "tre-prv.h"
 #include "tre-mem.h"
diff --git a/hawk/lib/tre-compile.c b/hawk/lib/tre-compile.c
index 2fa2de38..83647d12 100644
--- a/hawk/lib/tre-compile.c
+++ b/hawk/lib/tre-compile.c
@@ -1753,9 +1753,9 @@ tre_make_trans(hawk_gem_t* gem, tre_pos_and_tags_t *p1, tre_pos_and_tags_t *p2,
 					int *tags;
 
 					DPRINT(("	 %2d -> %2d on %3d", p1->position, p2->position,
-					        p1->code_min));
+					        (int)p1->code_min));
 					if (p1->code_max != p1->code_min)
-						DPRINT(("-%3d", p1->code_max));
+						DPRINT(("-%3d", (int)p1->code_max));
 					tags = trans->tags;
 					if (tags)
 					{
diff --git a/hawk/lib/tre-compile.h b/hawk/lib/tre-compile.h
index 56dacaa2..9580088c 100644
--- a/hawk/lib/tre-compile.h
+++ b/hawk/lib/tre-compile.h
@@ -59,8 +59,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 
-#ifndef _HAWK_LIB_CMN_TRE_COMPILE_H_
-#define _HAWK_LIB_CMN_TRE_COMPILE_H_
+#ifndef _HAWK_LIB_TRE_COMPILE_H_
+#define _HAWK_LIB_TRE_COMPILE_H_
 
 typedef struct
 {
diff --git a/hawk/lib/tre-match-bt.c b/hawk/lib/tre-match-bt.c
index 3a333544..3c2708af 100644
--- a/hawk/lib/tre-match-bt.c
+++ b/hawk/lib/tre-match-bt.c
@@ -231,7 +231,6 @@ tre_tnfa_run_backtrack(hawk_gem_t* gem, const tre_tnfa_t *tnfa, const void *stri
 	/* Current TNFA state. */
 	tre_tnfa_transition_t *state;
 	int *states_seen = NULL;
-
 	/* Memory allocator to for allocating the backtracking stack. */
 	tre_mem_t mem = tre_bt_mem_new(gem);
 
@@ -581,7 +580,8 @@ backtrack:
 			if (stack->prev)
 			{
 				DPRINT(("	 backtracking\n"));
-				if (stack->item.state->assertions && ASSERT_BACKREF)
+				/*if (stack->item.state->assertions && ASSERT_BACKREF)*/
+				if (stack->item.state->assertions & ASSERT_BACKREF)
 				{
 					DPRINT(("  states_seen[%d] = 0\n", stack->item.state_id));
 					states_seen[stack->item.state_id] = 0;
diff --git a/hawk/lib/tre-parse.h b/hawk/lib/tre-parse.h
index 2c0da71d..c55ef33a 100644
--- a/hawk/lib/tre-parse.h
+++ b/hawk/lib/tre-parse.h
@@ -58,8 +58,8 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-#ifndef _HAWK_LIB_CMN_TRE_PARSE_H_
-#define _HAWK_LIB_CMN_TRE_PARSE_H_
+#ifndef _HAWK_LIB_TRE_PARSE_H_
+#define _HAWK_LIB_TRE_PARSE_H_
 
 /* Parse context. */
 typedef struct
diff --git a/hawk/lib/tre-prv.h b/hawk/lib/tre-prv.h
index db49dc96..1c99a494 100644
--- a/hawk/lib/tre-prv.h
+++ b/hawk/lib/tre-prv.h
@@ -263,7 +263,24 @@ typedef hawk_ooci_t tre_cint_t;
 
 /* Define the character types and functions. */
 #ifdef TRE_WCHAR
-#	define TRE_CHAR_MAX HAWK_TYPE_MAX(hawk_uch_t)
+/* [HAWK]
+ * the TRE code uses the int type to represent a code point
+ * in various part. in fact, it uses int, long, tre_cint_t intermixedly.
+ * it's not easy to switch to a single type because lit->code_max is bitwise-ORed
+ * with the assertions field which is of the int type.
+ *
+ * if TRE_CHAR_MAX is greater than INT_MAX, some comparion fails as TRE_CHAR_MAX
+ * is treated as -1. here let me define TRE_CHAR_MAX to avoid this issue.
+ *
+ * however, if int is 2 bytes long,TRE_CHAR_MAX becomes 32767 which is way too small
+ * to represent even upper-half of the  UCS-2 codepoints.
+ */
+#	if (HAWK_SIZEOF_UCH_T < HAWK_SIZEOF_INT) 
+#		define TRE_CHAR_MAX HAWK_TYPE_MAX(hawk_uch_t)
+#	else
+#		define TRE_CHAR_MAX HAWK_TYPE_MAX(int)
+#	endif
+
 /*
 #	ifdef TRE_MULTIBYTE
 #		define TRE_MB_CUR_MAX (hawk_getmbcurmax())
@@ -313,6 +330,7 @@ struct tnfa_transition
 	/* END HAWK */
 	tre_cint_t code_min;
 	tre_cint_t code_max;
+
 	/* Pointer to the destination state. */
 	tre_tnfa_transition_t *state;
 	/* ID number of the destination state. */