diff --git a/ChangeLog b/ChangeLog
index 061d1dd77c..732c7956c2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sun Nov 22 17:59:50 2015  Naohisa Goto  <ngotogenome@gmail.com>
+
+	* configure.in: On Solaris, add -D_XOPEN_SOURCE=n only when both
+	  AC_TRY_CPP and AC_TRY_COMPILE pass, because some options
+	  (e.g. -std=iso9899:1999) are not set when running C preprocessor
+	  or building ext.
+
 Sun Nov 22 16:53:34 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* compile.c (iseq_peephole_optimize): remove unreachable code
diff --git a/configure.in b/configure.in
index 7c2a8c9ea1..d871904f59 100644
--- a/configure.in
+++ b/configure.in
@@ -1105,36 +1105,29 @@ main()
 		if test $given_xopen_source = no; then
 		  AC_MSG_CHECKING(appropriate _XOPEN_SOURCE value to define)
 		  define_xopen_source=""
-		  if test x"$define_xopen_source" = x; then
-			AC_TRY_COMPILE([
-			#define _XOPEN_SOURCE 700
+		  for tmp_xpg in 7 6 5; do
+		    if test x"$define_xopen_source" != x; then
+		        break
+		    fi
+		    # Both AC_TRY_CPP and AC_TRY_COMPILE should pass
+		    # because some options may not be set to CPPFLAGS.
+		    AC_TRY_CPP([
+			#define _XOPEN_SOURCE ${tmp_xpg}00
 			#include <unistd.h>
-			#ifndef _XPG7
-			#error _XPG7 should be defined by _XOPEN_SOURCE=700
+			#ifndef _XPG${tmp_xpg}
+			#error _XPG${tmp_xpg} should be defined by _XOPEN_SOURCE=${tmp_xpg}00
+			#endif
+			], [
+			AC_TRY_COMPILE([
+			#define _XOPEN_SOURCE ${tmp_xpg}00
+			#include <unistd.h>
+			#ifndef _XPG${tmp_xpg}
+			#error _XPG${tmp_xpg} should be defined by _XOPEN_SOURCE=${tmp_xpg}00
 			#endif
 			], [],
-			[define_xopen_source=700], [])
-		  fi
-		  if test x"$define_xopen_source" = x; then
-			AC_TRY_COMPILE([
-			#define _XOPEN_SOURCE 600
-			#include <unistd.h>
-			#ifndef _XPG6
-			#error _XPG6 should be defined by _XOPEN_SOURCE=600
-			#endif
-			], [],
-			[define_xopen_source=600], [])
-		  fi
-		  if test x"$define_xopen_source" = x; then
-			AC_TRY_COMPILE([
-			#define _XOPEN_SOURCE 500
-			#include <unistd.h>
-			#ifndef _XPG5
-			#error _XPG5 should be defined by _XOPEN_SOURCE=500
-			#endif
-			], [],
-			[define_xopen_source=500], [])
-		  fi
+			[define_xopen_source=${tmp_xpg}00], [])
+			], [])
+		  done
 		  if test x"$define_xopen_source" = x; then
 		    define_xopen_source=no
 		  fi