diff --git a/src/map.cpp b/src/map.cpp
index 9c06750b8..29bbbc0d9 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -2312,7 +2312,7 @@ void ServerMap::finishBlockMake(BlockMakeData *data,
 	{
 		// 70ms @cs=8
 		//TimeTaker timer("finishBlockMake() blitBackAll");
-		data->vmanip->blitBackAll(&changed_blocks);
+		data->vmanip->blitBackAll(&changed_blocks, false);
 	}
 
 	EMERGE_DBG_OUT("finishBlockMake: changed_blocks.size()=" << changed_blocks.size());
@@ -3586,7 +3586,8 @@ void ManualMapVoxelManipulator::initialEmerge(v3s16 blockpos_min,
 }
 
 void ManualMapVoxelManipulator::blitBackAll(
-		std::map<v3s16, MapBlock*> * modified_blocks)
+		std::map<v3s16, MapBlock*> *modified_blocks,
+		bool overwrite_generated)
 {
 	if(m_area.getExtent() == v3s16(0,0,0))
 		return;
@@ -3601,10 +3602,9 @@ void ManualMapVoxelManipulator::blitBackAll(
 		v3s16 p = i->first;
 		MapBlock *block = m_map->getBlockNoCreateNoEx(p);
 		bool existed = !(i->second & VMANIP_BLOCK_DATA_INEXIST);
-		if((existed == false) || (block == NULL))
-		{
+		if ((existed == false) || (block == NULL) ||
+			(overwrite_generated == false && block->isGenerated() == true))
 			continue;
-		}
 
 		block->copyFrom(*this);
 
diff --git a/src/map.h b/src/map.h
index 4972046f5..f4c7bb2fc 100644
--- a/src/map.h
+++ b/src/map.h
@@ -543,10 +543,11 @@ public:
 	{m_map = map;}
 
 	void initialEmerge(v3s16 blockpos_min, v3s16 blockpos_max,
-						bool load_if_inexistent = true);
+			bool load_if_inexistent = true);
 
 	// This is much faster with big chunks of generated data
-	void blitBackAll(std::map<v3s16, MapBlock*> * modified_blocks);
+	void blitBackAll(std::map<v3s16, MapBlock*> * modified_blocks,
+			bool overwrite_generated = true);
 
 protected:
 	bool m_create_area;