diff --git a/repos/libports/src/lib/libc/task.cc b/repos/libports/src/lib/libc/task.cc
index d398ff586..fd990e475 100644
--- a/repos/libports/src/lib/libc/task.cc
+++ b/repos/libports/src/lib/libc/task.cc
@@ -6,7 +6,7 @@
  */
 
 /*
- * Copyright (C) 2016-2017 Genode Labs GmbH
+ * Copyright (C) 2016-2018 Genode Labs GmbH
  *
  * This file is part of the Genode OS framework, which is distributed
  * under the terms of the GNU Affero General Public License version 3.
@@ -394,6 +394,8 @@ struct Libc::Kernel
 
 		Genode::Thread &_myself { *Genode::Thread::myself() };
 
+		addr_t _kernel_stack = Thread::mystack().top;
+
 		void *_user_stack = {
 			_myself.alloc_secondary_stack(_myself.name().string(),
 			                              Component::stack_size()) };
@@ -546,8 +548,8 @@ struct Libc::Kernel
 		unsigned long _suspend_main(Suspend_functor &check,
 		                            unsigned long timeout_ms)
 		{
-			/* check if we're running on the user context */
-			if (Thread::myself()->mystack().top != (Genode::addr_t)_user_stack) {
+			/* check that we're not running on libc kernel context */
+			if (Thread::mystack().top == _kernel_stack) {
 				error("libc suspend() called from non-user context (",
 				      __builtin_return_address(0), ") - aborting");
 				exit(1);