diff --git a/src/mapblock.cpp b/src/mapblock.cpp
index 1a94857af..ca5894794 100644
--- a/src/mapblock.cpp
+++ b/src/mapblock.cpp
@@ -367,7 +367,7 @@ void MapBlock::actuallyUpdateDayNightDiff()
 		Check if any lighting value differs
 	*/
 
-	MapNode previous_n;
+	MapNode previous_n(CONTENT_IGNORE);
 	for (u32 i = 0; i < nodecount; i++) {
 		MapNode n = data[i];