diff --git a/src/powder.c b/src/powder.c
index 3861248bb..83a180a58 100644
--- a/src/powder.c
+++ b/src/powder.c
@@ -3375,8 +3375,7 @@ int InCurrentBrush(int i, int j, int rx, int ry)
 			return (abs(i) <= rx && abs(j) <= ry);
 			break;
 		case TRI_BRUSH:
-			// -1e-9 because due to rounding errors, the corner at i=rx is not considered to be inside the brush at some brush sizes
-			return (j <= ry ) && ( j >= (((-2.0*ry)/rx)*i)-ry-1e-9) && ( j >= (((-2.0*ry)/(-rx))*i)-ry-1e-9) ;
+			return ((abs((rx+2*i)*ry+rx*j) + abs(2*rx*(j-ry)) + abs((rx-2*i)*ry+rx*j))<=(4*rx*ry));
 			break;
 		default:
 			return 0;