diff --git a/src/mapgen_v6.cpp b/src/mapgen_v6.cpp
index 7f5be27ae..d4b9201d9 100644
--- a/src/mapgen_v6.cpp
+++ b/src/mapgen_v6.cpp
@@ -56,6 +56,7 @@ MapgenV6::MapgenV6(int mapgenid, MapgenParams *params, EmergeManager *emerge)
 	this->ystride = csize.X; //////fix this
 
 	this->heightmap = new s16[csize.X * csize.Z];
+	memset(this->heightmap, 0, csize.X * csize.Z * sizeof(*this->heightmap));
 
 	MapgenV6Params *sp = (MapgenV6Params *)params->sparams;
 	this->spflags     = sp->spflags;