@@ -9,6 +9,11 @@ What's New in Stackless 3.X.X?
 
 *Release date: 20XX-XX-XX*
 
+- https://github.com/stackless-dev/stackless/issues/200
+  Fix a bug in the C-API functions PyTasklet_Run_nr() and
+  PyTasklet_Switch_nr(). Under exotic conditions the functions could
+  cause undefined behavior.
+
 - https://github.com/stackless-dev/stackless/issues/193
   Fix the macros PyTasklet_CheckExact(op) and PyChannel_CheckExact(op).
   Previously they contained a reference to a non existing variable.
 
@@ -800,7 +800,7 @@ impl_tasklet_run_remove(PyTaskletObject *task, int remove);
 int
 PyTasklet_Run_nr(PyTaskletObject *task)
 {
-    slp_try_stackless = 1;
+    STACKLESS_PROPOSE_ALL();
     return slp_return_wrapper(impl_tasklet_run_remove(task, 0));
 }
 
@@ -929,7 +929,7 @@ PyTasklet_Switch_M(PyTaskletObject *task)
 int
 PyTasklet_Switch_nr(PyTaskletObject *task)
 {
-    slp_try_stackless = 1;
+    STACKLESS_PROPOSE_ALL();
     return slp_return_wrapper(impl_tasklet_run_remove(task, 1));
 }
Original file line number	Diff line number	Diff line change
`@@ -800,7 +800,7 @@ impl_tasklet_run_remove(PyTaskletObject *task, int remove);`
`800`	`800`	`int`
`801`	`801`	`PyTasklet_Run_nr(PyTaskletObject *task)`
`802`	`802`	`{`
`803`		`- slp_try_stackless = 1;`
	`803`	`+ STACKLESS_PROPOSE_ALL();`
`804`	`804`	`return slp_return_wrapper(impl_tasklet_run_remove(task, 0));`
`805`	`805`	`}`
`806`	`806`
`@@ -929,7 +929,7 @@ PyTasklet_Switch_M(PyTaskletObject *task)`
`929`	`929`	`int`
`930`	`930`	`PyTasklet_Switch_nr(PyTaskletObject *task)`
`931`	`931`	`{`
`932`		`- slp_try_stackless = 1;`
	`932`	`+ STACKLESS_PROPOSE_ALL();`
`933`	`933`	`return slp_return_wrapper(impl_tasklet_run_remove(task, 1));`
`934`	`934`	`}`
`935`	`935`