diff --git a/src/mapblock.cpp b/src/mapblock.cpp
index 9dbd63cc4..fcde1a5d1 100644
--- a/src/mapblock.cpp
+++ b/src/mapblock.cpp
@@ -210,10 +210,7 @@ void MapBlock::copyTo(VoxelManipulator &dst)
 	v3s16 data_size(MAP_BLOCKSIZE, MAP_BLOCKSIZE, MAP_BLOCKSIZE);
 	VoxelArea data_area(v3s16(0,0,0), data_size - v3s16(1,1,1));
 
-	if (m_is_mono_block) {
-		reallocate(nodecount, data[0]);
-		m_is_mono_block = false;
-	}
+	deconvertMonoblock();
 	// Copy from data to VoxelManipulator
 	dst.copyFrom(data, data_area, v3s16(0,0,0),
 			getPosRelative(), data_size);
@@ -224,18 +221,16 @@ void MapBlock::copyFrom(const VoxelManipulator &src)
 	v3s16 data_size(MAP_BLOCKSIZE, MAP_BLOCKSIZE, MAP_BLOCKSIZE);
 	VoxelArea data_area(v3s16(0,0,0), data_size - v3s16(1,1,1));
 
-	if (m_is_mono_block) {
-		reallocate(nodecount, data[0]);
-		m_is_mono_block = false;
-	}
+	deconvertMonoblock();
 	// Copy from VoxelManipulator to data
 	src.copyTo(data, data_area, v3s16(0,0,0),
 			getPosRelative(), data_size);
 
-	checkForMonoblock();
+	tryConvertToMonoblock();
 }
 
-void MapBlock::checkForMonoblock() {
+void MapBlock::tryConvertToMonoblock()
+{
 	if (m_is_mono_block)
 		return;
 
@@ -258,6 +253,14 @@ void MapBlock::checkForMonoblock() {
 	}
 }
 
+void MapBlock::deconvertMonoblock()
+{
+	if (m_is_mono_block) {
+		reallocate(nodecount, data[0]);
+		m_is_mono_block = false;
+	}
+}
+
 void MapBlock::actuallyUpdateIsAir()
 {
 	// Running this function un-expires m_is_air
@@ -635,7 +638,7 @@ void MapBlock::deSerialize(std::istream &in_compressed, u8 version, bool disk)
 		}
 
 		if (nimap.size() == 1) {
-			checkForMonoblock();
+			tryConvertToMonoblock();
 			u16 dummy;
 			if (nimap.getId("air", dummy)) {
 				m_is_air = true;
diff --git a/src/mapblock.h b/src/mapblock.h
index debeb52fe..06764b055 100644
--- a/src/mapblock.h
+++ b/src/mapblock.h
@@ -75,10 +75,7 @@ public:
 
 	MapNode* getData()
 	{
-		if (m_is_mono_block) {
-			reallocate(nodecount, data[0]);
-			m_is_mono_block = false;
-		}
+		deconvertMonoblock();
 		return data;
 	}
 
@@ -255,10 +252,7 @@ public:
 		if (!isValidPosition(x, y, z))
 			throw InvalidPositionException();
 
-		if (m_is_mono_block) {
-			reallocate(nodecount, data[0]);
-			m_is_mono_block = false;
-		}
+		deconvertMonoblock();
 		data[z * zstride + y * ystride + x] = n;
 		raiseModified(MOD_STATE_WRITE_NEEDED, MOD_REASON_SET_NODE);
 	}
@@ -287,10 +281,7 @@ public:
 
 	inline void setNodeNoCheck(s16 x, s16 y, s16 z, MapNode n)
 	{
-		if (m_is_mono_block) {
-			reallocate(nodecount, data[0]);
-			m_is_mono_block = false;
-		}
+		deconvertMonoblock();
 		data[z * zstride + y * ystride + x] = n;
 		raiseModified(MOD_STATE_WRITE_NEEDED, MOD_REASON_SET_NODE);
 	}
@@ -449,7 +440,8 @@ private:
 	*/
 
 	void deSerialize_pre22(std::istream &is, u8 version, bool disk);
-	void checkForMonoblock();
+	void tryConvertToMonoblock();
+	void deconvertMonoblock();
 
 	void reallocate(u32 c, MapNode n)
 	{
@@ -497,11 +489,11 @@ private:
 	short m_refcount = 0;
 
 	/*
-	 * Note that this is not an inline array because that has implications for
-	 * heap fragmentation (the array is exactly 16K), CPU caches and/or
-	 * optimizability of algorithms working on this array.
+	 * Note that this is not an inline array because that has implications for heap
+	 * fragmentation (the array is exactly 16K, or exactly 4 bytes for a "monoblock"),
+	 * CPU caches and/or optimizability of algorithms working on this array.
 	 */
-	MapNode * data = nullptr; // of `nodecount` elements
+	MapNode * data = nullptr;
 
 	// provides the item and node definitions
 	IGameDef *m_gamedef;