diff --git a/ChangeLog b/ChangeLog
index 49fc09c8d8..6d9a4403ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Oct 23 16:43:43 2011  Naohisa Goto  <ngotogenome@gmail.com>
+
+	* ext/io/wait/wait.c: ioctl(2) is declared in unistd.h on Solaris.
+
 Sun Oct 23 16:33:35 2011  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* ext/tk/MANUAL_tcltklib.eng: fix typo. reported by Mimura-san.
diff --git a/ext/io/wait/wait.c b/ext/io/wait/wait.c
index 34e832b122..eb7ed03cea 100644
--- a/ext/io/wait/wait.c
+++ b/ext/io/wait/wait.c
@@ -14,6 +14,9 @@
 #include "ruby/io.h"
 
 #include <sys/types.h>
+#if defined(HAVE_UNISTD_H) && (defined(__sun) || defined(__sun__))
+#include <unistd.h>
+#endif
 #if defined(HAVE_SYS_IOCTL_H)
 #include <sys/ioctl.h>
 #endif