diff --git a/internal/opengl/context_js.go b/internal/opengl/context_js.go
index b7284a34e..6e611b03d 100644
--- a/internal/opengl/context_js.go
+++ b/internal/opengl/context_js.go
@@ -371,7 +371,7 @@ func (c *Context) UniformFloats(p Program, location string, v []float32) {
 		gl.Call("uniform4f", js.Value(l), v[0], v[1], v[2], v[3])
 	case 16:
 		u8 := js.ValueOf(v)
-		m := float32Array.New(u8.Get("buffer"), u8.Get("byteOffset").Int(), 16)
+		m := float32Array.New(u8.Get("buffer"), u8.Get("byteOffset"), 16)
 		gl.Call("uniformMatrix4fv", js.Value(l), false, m)
 	default:
 		panic("not reached")