diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 14888b4edfe..9f930361ee1 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -645,8 +645,9 @@ impl WebGLRenderingContext {
             },
             (TexFormat::RGBA, TexDataType::UnsignedShort5551) => {
                 for rgba in pixels.chunks_mut(2) {
-                    let pix = NativeEndian::read_u16(rgba);
-                    NativeEndian::write_u16(rgba, if pix & (1 << 15) != 0 { pix } else { 0 });
+                    if NativeEndian::read_u16(rgba) & 1 == 0 {
+                        NativeEndian::write_u16(rgba, 0);
+                    }
                 }
             },
             (TexFormat::RGBA, TexDataType::UnsignedShort4444) => {
diff --git a/tests/wpt/webgl/meta/conformance/textures/misc/tex-image-with-format-and-type.html.ini b/tests/wpt/webgl/meta/conformance/textures/misc/tex-image-with-format-and-type.html.ini
index aca89365106..cc7d66b3a16 100644
--- a/tests/wpt/webgl/meta/conformance/textures/misc/tex-image-with-format-and-type.html.ini
+++ b/tests/wpt/webgl/meta/conformance/textures/misc/tex-image-with-format-and-type.html.ini
@@ -2,12 +2,6 @@
   [WebGL test #65: UNPACK_PREMULTIPLY_ALPHA_WEBGL with RGBA/UNSIGNED_SHORT_4_4_4_4]
     expected: FAIL
 
-  [WebGL test #66: UNPACK_PREMULTIPLY_ALPHA_WEBGL with RGBA/UNSIGNED_SHORT_5_5_5_1]
-    expected: FAIL
-
   [WebGL test #69: UNPACK_PREMULTIPLY_ALPHA_WEBGL with RGBA/UNSIGNED_SHORT_4_4_4_4]
     expected: FAIL
 
-  [WebGL test #70: UNPACK_PREMULTIPLY_ALPHA_WEBGL with RGBA/UNSIGNED_SHORT_5_5_5_1]
-    expected: FAIL
-