diff --git a/configure.in b/configure.in
index 59dc86f04..e77238556 100644
--- a/configure.in
+++ b/configure.in
@@ -390,7 +390,8 @@ AC_CHECK_FUNC(
 		 #include <sys/syscall.h>],
 		[int main() {
 			return syscall(SYS_gettid);}],
-		[AC_MSG_RESULT([yes]); AC_DEFINE([HAVE_SYS_GETTID])],
+		[AC_MSG_RESULT([yes]); AC_DEFINE([HAVE_GETTID])
+		 AC_DEFINE([HAVE_SYS_GETTID])],
 		[AC_MSG_RESULT([no])]
 	)]
 )
diff --git a/src/libstrongswan/threading/thread.c b/src/libstrongswan/threading/thread.c
index 0cbd97c3f..49a1b8430 100644
--- a/src/libstrongswan/threading/thread.c
+++ b/src/libstrongswan/threading/thread.c
@@ -20,15 +20,16 @@
 
 #ifdef HAVE_GETTID
 #include <sys/types.h>
-#elif defined(HAVE_SYS_GETTID)
 #include <unistd.h>
+#endif
+
+#ifdef HAVE_SYS_GETTID
 #include <sys/syscall.h>
 static inline pid_t gettid()
 {
 	return syscall(SYS_gettid);
 }
-#define HAVE_GETTID
-#endif /* HAVE_SYS_GETTID */
+#endif
 
 #include <library.h>
 #include <debug.h>