diff --git a/src/simulation/Air.cpp b/src/simulation/Air.cpp
index 455b62c7e..aa541578e 100644
--- a/src/simulation/Air.cpp
+++ b/src/simulation/Air.cpp
@@ -133,7 +133,7 @@ void Air::update_airh(void)
 			auto j = (int)ty;
 			tx -= i;
 			ty -= j;
-			if (!(bmap_blockairh[y][x]&0x8) && i>=2 && i<=XCELLS-3 && j>=2 && j<=YCELLS-3)
+			if (!(bmap_blockairh[y][x]&0x8) && i>=2 && i<XCELLS-3 && j>=2 && j<YCELLS-3)
 			{
 				auto odh = dh;
 				dh *= 1.0f - AIR_VADV;
@@ -333,7 +333,7 @@ void Air::update_air(void)
 				auto j = (int)ty;
 				tx -= i;
 				ty -= j;
-				if (!bmap_blockair[y][x] && i>=2 && i<=XCELLS-3 && j>=2 && j<=YCELLS-3)
+				if (!bmap_blockair[y][x] && i>=2 && i<XCELLS-3 && j>=2 && j<YCELLS-3)
 				{
 					dx *= 1.0f - AIR_VADV;
 					dy *= 1.0f - AIR_VADV;