diff --git a/simap.h b/simap.h
index 2955228..bbaf8a8 100644
--- a/simap.h
+++ b/simap.h
@@ -231,8 +231,9 @@ static inline void* simap(void *amap_instance, AMAP_OP op, const char *key, void
 	simap_instance *map = (simap_instance *) amap_instance;
 
 	if(op == AMAP_ERASE) {
+		map->prev_usage_end = (uint32_t) -1;
 		map->usage_end = 0;
-		return NULL;
+		return (void *)((uint8_t)(NULL) - 1L);
 	}
 
 	/* Search for the key - also needed for SET in order to "re-set" */