diff --git a/Include/pystate.h b/Include/pystate.h
index 4919d99..0681e65 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -61,6 +61,10 @@
 
     struct _frame *frame;
     int recursion_depth;
+    char overflowed; /* The stack has overflowed. Allow 50 more calls
+		        to handle the runtime error. */
+    char recursion_critical; /* The current calls must not cause 
+				a stack overflow. */
     /* 'tracing' keeps track of the execution depth when tracing/profiling.
        This is to prevent the actual trace/profile code from being recorded in
        the trace/profile. */