--- a/regexParser/grepWalk.cc	Tue Jan 19 14:52:33 2016 +0900
+++ b/regexParser/grepWalk.cc	Tue Jan 19 17:16:37 2016 +0900
@@ -15,6 +15,7 @@
 
 void grep(TransitionGeneratorPtr tg,Buffer buff,unsigned long d) {
     unsigned char c = *buff.buffptr++;
+    if (c=='\0') return;
     StatePtr state = tg->stateList;
     bool found = false;
 
@@ -25,8 +26,13 @@
         cc = getNext(ccw);
         unsigned long begin = cc->cond.range.begin;
         unsigned long end = cc->cond.range.end;
-        if (c < begin) found = false;
-        else if (c < end) found = true;
+        if (begin == end) {
+            if (c == begin) found = true;
+            else found = false;
+        } else {
+            if (c < begin) found = false;
+            else if (c < end) found = true;
+        }
         if (found == true) break;
     }