diff --git a/src/draw/sw/lv_draw_sw_mask.c b/src/draw/sw/lv_draw_sw_mask.c
index 74c0869f6..d9152d5c4 100644
--- a/src/draw/sw/lv_draw_sw_mask.c
+++ b/src/draw/sw/lv_draw_sw_mask.c
@@ -451,7 +451,7 @@ LV_ATTRIBUTE_FAST_MEM static lv_draw_sw_mask_res_t lv_draw_mask_line(lv_opa_t *
             /*Non sense: Can't be on the right/left of a horizontal line*/
             if(p->cfg.side == LV_DRAW_SW_MASK_LINE_SIDE_LEFT ||
                p->cfg.side == LV_DRAW_SW_MASK_LINE_SIDE_RIGHT) return LV_DRAW_SW_MASK_RES_FULL_COVER;
-            else if(p->cfg.side == LV_DRAW_SW_MASK_LINE_SIDE_TOP && abs_y + 1 < 0) return LV_DRAW_SW_MASK_RES_FULL_COVER;
+            else if(p->cfg.side == LV_DRAW_SW_MASK_LINE_SIDE_TOP && abs_y < 0) return LV_DRAW_SW_MASK_RES_FULL_COVER;
             else if(p->cfg.side == LV_DRAW_SW_MASK_LINE_SIDE_BOTTOM && abs_y > 0) return LV_DRAW_SW_MASK_RES_FULL_COVER;
             else {
                 return LV_DRAW_SW_MASK_RES_TRANSP;
diff --git a/src/draw/sw/lv_draw_sw_triangle.c b/src/draw/sw/lv_draw_sw_triangle.c
index f2b1eaec8..311325b3d 100644
--- a/src/draw/sw/lv_draw_sw_triangle.c
+++ b/src/draw/sw/lv_draw_sw_triangle.c
@@ -104,9 +104,15 @@ void lv_draw_sw_triangle(lv_draw_unit_t * draw_unit, const lv_draw_triangle_dsc_
                                      p[2].x, p[2].y,
                                      right ? LV_DRAW_SW_MASK_LINE_SIDE_LEFT : LV_DRAW_SW_MASK_LINE_SIDE_RIGHT);
 
-    lv_draw_sw_mask_line_points_init(&mask_bottom, p[1].x, p[1].y,
-                                     p[2].x, p[2].y,
-                                     right ? LV_DRAW_SW_MASK_LINE_SIDE_LEFT : LV_DRAW_SW_MASK_LINE_SIDE_RIGHT);
+    if(p[1].y == p[2].y) {
+        lv_draw_sw_mask_line_points_init(&mask_bottom, p[1].x, p[1].y,
+                                         p[2].x, p[2].y, LV_DRAW_SW_MASK_LINE_SIDE_TOP);
+    }
+    else {
+        lv_draw_sw_mask_line_points_init(&mask_bottom, p[1].x, p[1].y,
+                                         p[2].x, p[2].y,
+                                         right ? LV_DRAW_SW_MASK_LINE_SIDE_LEFT  : LV_DRAW_SW_MASK_LINE_SIDE_RIGHT);
+    }
 
     masks[0] = &mask_left;
     masks[1] = &mask_right;
diff --git a/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_128.png b/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_128.png
index 4aeeb5580..818ce909d 100644
Binary files a/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_128.png and b/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_128.png differ
diff --git a/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_255.png b/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_255.png
index c4c942745..116d0d158 100644
Binary files a/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_255.png and b/tests/ref_imgs/draw/render/argb8888/demo_render_triangle_opa_255.png differ
diff --git a/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_128.png b/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_128.png
index 372bdc3ec..b431f8014 100644
Binary files a/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_128.png and b/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_128.png differ
diff --git a/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_255.png b/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_255.png
index 507032474..de2a3b2cb 100644
Binary files a/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_255.png and b/tests/ref_imgs/draw/render/rgb565/demo_render_triangle_opa_255.png differ
diff --git a/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_128.png b/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_128.png
index 95f7fc463..f5ed95738 100644
Binary files a/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_128.png and b/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_128.png differ
diff --git a/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_255.png b/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_255.png
index fdc86a070..1ec312688 100644
Binary files a/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_255.png and b/tests/ref_imgs/draw/render/rgb888/demo_render_triangle_opa_255.png differ
diff --git a/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_128.png b/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_128.png
index 95f7fc463..f5ed95738 100644
Binary files a/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_128.png and b/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_128.png differ
diff --git a/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_255.png b/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_255.png
index fdc86a070..1ec312688 100644
Binary files a/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_255.png and b/tests/ref_imgs/draw/render/xrgb8888/demo_render_triangle_opa_255.png differ