diff --git a/src/map.c b/src/map.c
index 0b0260dd0..df382d93b 100644
--- a/src/map.c
+++ b/src/map.c
@@ -1627,8 +1627,10 @@ bool fireOnLocation(unsigned int x, unsigned int y)
 	return psTile != NULL && TileIsBurning(psTile);
 }
 
-static void dangerFloodFill(int player)
+// This function runs in a separate thread!
+static int dangerFloodFill(WZ_DECL_UNUSED void *data)
 {
+	int player = lastDangerPlayer;
 	int i;
 	Vector2i pos = getPlayerStartPosition(player);
 	Vector2i npos;
@@ -1690,6 +1692,7 @@ static void dangerFloodFill(int player)
 			pos.y = floodbucket[bucketcounter].y;
 		}
 	} while (bucketcounter);
+	return 0;
 }
 
 // This function runs in a separate thread!
diff --git a/src/structure.c b/src/structure.c
index 5bdf44fac..f6448decf 100644
--- a/src/structure.c
+++ b/src/structure.c
@@ -1716,6 +1716,11 @@ STRUCTURE* buildStructureDir(STRUCTURE_STATS *pStructureType, UDWORD x, UDWORD y
 			}
 		}
 
+		if (pStructureType->type != REF_REARM_PAD && pStructureType->type != REF_GATE)
+		{
+			auxStructureBlocking(psBuilding);
+		}
+
 		for (width = 0; width < sWidth; width++)
 		{
 			for (breadth = 0; breadth < sBreadth; breadth++)