diff --git a/ChangeLog b/ChangeLog
index 833b2a7713..0da562833b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue May  3 22:55:07 2016  Yuichiro Kaneko  <yui-knk@ruby-lang.org>
+
+	* complex.c (rb_complex_set_imag): Fix to properly set imag
+	  of complex.
+
 Tue May  3 22:19:55 2016  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* configure.in (warnflags): use -std=gnu99 instead of
diff --git a/complex.c b/complex.c
index 0d4073018d..ef3c01d0f8 100644
--- a/complex.c
+++ b/complex.c
@@ -1411,7 +1411,7 @@ rb_complex_set_real(VALUE cmp, VALUE r)
 VALUE
 rb_complex_set_imag(VALUE cmp, VALUE i)
 {
-    RCOMPLEX_SET_REAL(cmp, i);
+    RCOMPLEX_SET_IMAG(cmp, i);
     return cmp;
 }