--- a/psycopg/config.h
+++ b/psycopg/config.h
@@ -141,7 +141,9 @@
 #endif
 #endif
 
-#if (defined(__FreeBSD__) && __FreeBSD_version < 503000) || (defined(_WIN32) && !defined(__GNUC__)) || defined(__sun__) || defined(sun)
+#if (defined(__FreeBSD__) && __FreeBSD_version < 503000) ||    \
+  (defined(_WIN32) && !defined(__GNUC__)) ||                   \
+  defined(sunos_5_8)
 /* what's this, we have no round function either? */
 static double round(double num)
 {
--- a/setup.py
+++ b/setup.py
@@ -450,6 +450,11 @@
     'typecast_builtins.c', 'typecast_datetime.c',
 ]
 
+# We need to be able to distinguish solaris 8, 9 and 10.
+if os.uname()[0] == 'SunOS':
+    name = '%s_%s' % (os.uname()[0].lower(), os.uname()[2].replace('.', '_'))
+    define_macros.append((name, '1'))
+
 parser = configparser.ConfigParser()
 parser.read('setup.cfg')