diff --git a/src/corelib/global/qsystemdetection.h b/src/corelib/global/qsystemdetection.h
index a2e51fa3300..02e2f77c6b4 100644
--- a/src/corelib/global/qsystemdetection.h
+++ b/src/corelib/global/qsystemdetection.h
@@ -166,6 +166,8 @@
 #  define Q_OS_QNX
 #elif defined(__INTEGRITY)
 #  define Q_OS_INTEGRITY
+#elif defined(__rtems__)
+#  define Q_OS_RTEMS
 #elif defined(VXWORKS) /* there is no "real" VxWorks define - this has to be set in the mkspec! */
 #  define Q_OS_VXWORKS
 #elif defined(__HAIKU__)