diff --git a/Changelog-Trunk.txt b/Changelog-Trunk.txt
index 8079b0a1c2..0751658ee5 100644
--- a/Changelog-Trunk.txt
+++ b/Changelog-Trunk.txt
@@ -4,6 +4,8 @@ AS OF SVN REV. 5091, WE ARE NOW USING TRUNK.  ALL UNTESTED BUGFIXES/FEATURES GO
 IF YOU HAVE A WORKING AND TESTED BUGFIX PUT IT INTO STABLE AS WELL AS TRUNK.
 
 2006/09/09
+	* Added a crash protection in case mapfreeblock unlock tries to free a null
+	  pointer. [Skotlex]
 	* Moved perfect_hiding from state to special_state, so that it clears out
 	  when you remove your pet. [Skotlex]
 	* Probably fixed the Taekwon Rest skills. [Skotlex]
diff --git a/src/map/map.c b/src/map/map.c
index 4922831254..c57902f329 100644
--- a/src/map/map.c
+++ b/src/map/map.c
@@ -271,6 +271,7 @@ unsigned int distance(int dx, int dy) {
  */
 int map_freeblock (struct block_list *bl)
 {
+	nullpo_retr(block_free_lock, bl);
 	if (block_free_lock == 0 || block_free_count >= block_free_max)
 	{
 		aFree(bl);
@@ -308,7 +309,7 @@ int map_freeblock_unlock_sub(char *file, int lineno)
 		{	//Directly calling aFree shouldn't be a leak, as Free remembers the size the original pointed to memory was allocated with? [Skotlex]
 //			aFree(block_free[i]);
 //			_mfree(block_free[i], file, lineno, __func__);
-			_mfree(block_free[i], file, block_free[i]->type*100000+lineno, __func__);
+			_mfree(block_free[i], file, ((block_free[i]?block_free[i]->type:0)*100000)+lineno, __func__);
 			block_free[i] = NULL;
 		}
 		block_free_count = 0;