diff --git a/src/include/OpenImageIO/imagebufalgo.h b/src/include/OpenImageIO/imagebufalgo.h
index 183f1c574a..b866076783 100644
--- a/src/include/OpenImageIO/imagebufalgo.h
+++ b/src/include/OpenImageIO/imagebufalgo.h
@@ -405,9 +405,11 @@ ROI OIIO_API text_size (string_view text, int fontsize=16,
 ///             `channelvalues[i]` rather than copy any channel from `src`.
 ///             If `channelorder` itself is empty, the implied channel order
 ///             will be `{0, 1, ..., nchannels-1}`, meaning that it's only
-///             renaming channels, not reordering them.
+///             renaming, truncating, or extending channels, not reordering
+///             the channels that are already present.
 /// @param  channelvalues Fill values for color channels in which
-///             `channelorder[i]` < 0.
+///             `channelorder[i]` < 0. This can be empty if no channels are
+///             to be filled with constant values.
 /// @param  newchannelnames
 ///             An array of new channel names. Channels for which this
 ///             specifies an empty string will have their name taken from
diff --git a/src/libOpenImageIO/maketexture.cpp b/src/libOpenImageIO/maketexture.cpp
index ec6730928e..632b64941b 100644
--- a/src/libOpenImageIO/maketexture.cpp
+++ b/src/libOpenImageIO/maketexture.cpp
@@ -1345,6 +1345,7 @@ make_texture_impl(ImageBufAlgo::MakeTextureMode mode, const ImageBuf* input,
                 << "  Monochrome image detected. Converting to single channel texture.\n";
         std::shared_ptr<ImageBuf> newsrc(new ImageBuf(src->spec()));
         ImageBufAlgo::channels(*newsrc, *src, 1, NULL, NULL, NULL, true);
+        newsrc->specmod().default_channel_names();
         std::swap(src, newsrc);
     }