diff --git a/ChangeLog b/ChangeLog
index ee8afb4780..842cac4351 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Jan 11 23:40:21 2012  Naohisa Goto  <ngoto@gen-info.osaka-u.ac.jp>
+
+	* string.c (rb_str_concat): set array element after definition
+	  to fix compile error with Fujitsu C Compiler 5.6 on Solaris 10
+	  on Sparc.  [Bug #5878] [ruby-dev:45123]
+
 Wed Jan 11 22:52:51 2012  CHIKANAGA Tomoyuki  <nagachika00@gmail.com>
 
 	* gc.c (ruby_mimmalloc): don't set allocated size to header.
diff --git a/string.c b/string.c
index 55691d017c..9fd2480fd3 100644
--- a/string.c
+++ b/string.c
@@ -2093,7 +2093,8 @@ rb_str_concat(VALUE str1, VALUE str2)
 
     if (enc == rb_usascii_encoding()) {
 	/* US-ASCII automatically extended to ASCII-8BIT */
-	char buf[1] = {(char)code};
+	char buf[1];
+	buf[0] = (char)code;
 	if (code > 0xFF) {
 	    rb_raise(rb_eRangeError, "%u out of char range", code);
 	}