Index: libcfa/src/concurrency/invoke.h
===================================================================
--- libcfa/src/concurrency/invoke.h	(revision 7f81ef4cb49a428170b67848df1d825446c4835f)
+++ libcfa/src/concurrency/invoke.h	(revision 878cfcc025be2d89d167ef9fdf1b60ca2d6941b5)
@@ -214,4 +214,5 @@
 
 		#if defined( __CFA_WITH_VERIFY__ )
+			struct processor * volatile executing;
 			void * canary;
 		#endif
Index: libcfa/src/concurrency/kernel.cfa
===================================================================
--- libcfa/src/concurrency/kernel.cfa	(revision 7f81ef4cb49a428170b67848df1d825446c4835f)
+++ libcfa/src/concurrency/kernel.cfa	(revision 878cfcc025be2d89d167ef9fdf1b60ca2d6941b5)
@@ -321,4 +321,5 @@
 		/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->curr_cor == proc_cor || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
 		/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->curr_cor == proc_cor || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
+		/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, this, __ATOMIC_SEQ_CST) == 0p );
 		/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
 
@@ -332,8 +333,9 @@
 
 		/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
+		/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, 0p, __ATOMIC_SEQ_CST) == this );
 		/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
 		/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
+		/* paranoid */ verify( thrd_dst->state != Halted );
 		/* paranoid */ verify( thrd_dst->context.SP );
-		/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
 		/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
 		/* paranoid */ verify( ! __preemption_enabled() );
Index: libcfa/src/concurrency/kernel/startup.cfa
===================================================================
--- libcfa/src/concurrency/kernel/startup.cfa	(revision 7f81ef4cb49a428170b67848df1d825446c4835f)
+++ libcfa/src/concurrency/kernel/startup.cfa	(revision 878cfcc025be2d89d167ef9fdf1b60ca2d6941b5)
@@ -529,4 +529,5 @@
 	random_state = __global_random_mask ? __global_random_prime : __global_random_prime ^ rdtscl();
 	#if defined( __CFA_WITH_VERIFY__ )
+		executing = 0p;
 		canary = 0x0D15EA5E0D15EA5Ep;
 	#endif
Index: libcfa/src/concurrency/thread.cfa
===================================================================
--- libcfa/src/concurrency/thread.cfa	(revision 7f81ef4cb49a428170b67848df1d825446c4835f)
+++ libcfa/src/concurrency/thread.cfa	(revision 878cfcc025be2d89d167ef9fdf1b60ca2d6941b5)
@@ -50,4 +50,5 @@
 	random_state = __global_random_mask ? __global_random_prime : __global_random_prime ^ rdtscl();
 	#if defined( __CFA_WITH_VERIFY__ )
+		executing = 0p;
 		canary = 0x0D15EA5E0D15EA5Ep;
 	#endif