diff --git a/ChangeLog b/ChangeLog
index 8cc623d8c9..8b0ca7285a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Feb  5 12:11:04 2014  Koichi Sasada  <ko1@atdot.net>
+
+	* string.c (RESIZE_CAPA): should not resize shared string.
+
 Wed Feb  5 11:46:42 2014  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (gc_mark_children): STR_ASSOC is no longer available.
diff --git a/string.c b/string.c
index 86ae2bf6db..5df2ca38c0 100644
--- a/string.c
+++ b/string.c
@@ -107,9 +107,9 @@ VALUE rb_cSymbol;
 	}\
     }\
     else {\
+	assert(!FL_TEST((str), STR_SHARED)); \
 	REALLOC_N(RSTRING(str)->as.heap.ptr, char, (capacity)+termlen);\
-	if (!STR_NOCAPA_P(str))\
-	    RSTRING(str)->as.heap.aux.capa = (capacity);\
+	RSTRING(str)->as.heap.aux.capa = (capacity);\
     }\
 } while (0)