diff --git a/res/res_http_post.c b/res/res_http_post.c
index 7b0005dc7e..a77ef0d6f5 100644
--- a/res/res_http_post.c
+++ b/res/res_http_post.c
@@ -36,7 +36,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <gmime/gmime.h>
-#if defined (__OpenBSD__) || defined(__FreeBSD__) || defined(__DragonFly__) || defined(__NetBSD__) || defined(__Darwin__)
+#if defined(__OpenBSD__) || defined(__FreeBSD__) || defined(__DragonFly__) || defined(__NetBSD__) || defined(__Darwin__) || defined(SOLARIS)
 #include <libgen.h>
 #endif