diff --git a/lib/graphics.c b/lib/graphics.c
index 3e16be9..304d145 100644
--- a/lib/graphics.c
+++ b/lib/graphics.c
@@ -947,10 +947,10 @@ void draw_rounded_rectangle(gfx_context_t * ctx, int32_t x, int32_t y, uint16_t
 			}
 
 			GFX(ctx, _x, _y) = alpha_blend_rgba(GFX(ctx, _x, _y), c);
-			GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), c);
+			if (_z >= 0) GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), c);
 			_x = x + radius - i - 1;
 			GFX(ctx, _x, _y) = alpha_blend_rgba(GFX(ctx, _x, _y), c);
-			GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), c);
+			if (_z >= 0) GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), c);
 		}
 	}
 }
@@ -990,10 +990,10 @@ void draw_rounded_rectangle_pattern(gfx_context_t * ctx, int32_t x, int32_t y, u
 
 			double alpha = (j_max - (double)j);
 			GFX(ctx, _x, _y) = alpha_blend_rgba(GFX(ctx, _x, _y), pattern(_x,_y,alpha,extra));
-			GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), pattern(_x,_z,alpha,extra));
+			if (_z >= 0) GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), pattern(_x,_z,alpha,extra));
 			_x = x + radius - i - 1;
 			GFX(ctx, _x, _y) = alpha_blend_rgba(GFX(ctx, _x, _y), pattern(_x,_y,alpha,extra));
-			GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), pattern(_x,_z,alpha,extra));
+			if (_z >= 0) GFX(ctx, _x, _z) = alpha_blend_rgba(GFX(ctx, _x, _z), pattern(_x,_z,alpha,extra));
 		}
 	}
 }