diff --git a/src/sna/sna_trapezoids.c b/src/sna/sna_trapezoids.c
index 1a4b109d..95e7d4f8 100644
--- a/src/sna/sna_trapezoids.c
+++ b/src/sna/sna_trapezoids.c
@@ -4417,7 +4417,8 @@ struct inplace {
 static force_inline uint8_t coverage_opacity(int coverage, uint8_t opacity)
 {
 	coverage = coverage * 256 / FAST_SAMPLES_XY;
-	return mul_8_8(coverage - (coverage >> 8), opacity);
+	coverage -= coverage >> 8;
+	return opacity == 255 ? coverage : mul_8_8(coverage, opacity);
 }
 
 static void