diff --git a/libheif/plugins/encoder_kvazaar.cc b/libheif/plugins/encoder_kvazaar.cc
index a32886b926..9db79a6c2d 100644
--- a/libheif/plugins/encoder_kvazaar.cc
+++ b/libheif/plugins/encoder_kvazaar.cc
@@ -348,14 +348,17 @@ static void append_chunk_data(kvz_data_chunk* data, std::vector<uint8_t>& out)
 }
 
 
-static void copy_plane(kvz_pixel* out_p, uint32_t out_stride, const uint8_t* in_p, uint32_t in_stride, int w, int h, int padded_width, int padded_height)
+static void copy_plane(kvz_pixel* out_p, uint32_t out_stride, const uint8_t* in_p, uint32_t in_stride, int w, int h, int padded_width, int padded_height,
+                       int bit_depth)
 {
+  int bpp = (bit_depth > 8) ? 2 : 1;
+
   for (int y = 0; y < padded_height; y++) {
     int sy = std::min(y, h - 1); // source y
-    memcpy(out_p + y * out_stride, in_p + sy * in_stride, w);
+    memcpy(out_p + y * out_stride, in_p + sy * in_stride, w * bpp);
 
     if (padded_width > w) {
-      memset(out_p + y * out_stride + w, *(in_p + sy * in_stride + w - 1), padded_width - w);
+      memset(out_p + y * out_stride + w, *(in_p + sy * in_stride + w - 1), (padded_width - w) * bpp);
     }
   }
 }
@@ -372,9 +375,22 @@ static struct heif_error kvazaar_encode_image(void* encoder_raw, const struct he
   struct encoder_struct_kvazaar* encoder = (struct encoder_struct_kvazaar*) encoder_raw;
 
   int bit_depth = heif_image_get_bits_per_pixel_range(image, heif_channel_Y);
+  int bit_depth_chroma = 0;
   bool isGreyscale = (heif_image_get_colorspace(image) == heif_colorspace_monochrome);
   heif_chroma chroma = heif_image_get_chroma_format(image);
 
+  if (!isGreyscale) {
+    bit_depth_chroma = heif_image_get_bits_per_pixel_range(image, heif_channel_Cb);
+    if (bit_depth != bit_depth_chroma) {
+      struct heif_error err = {
+          heif_error_Encoder_plugin_error,
+          heif_suberror_Unsupported_bit_depth,
+          "Luma bit depth must equal the chroma bit depth"
+      };
+      return err;
+    }
+  }
+
   // Kvazaar uses a hard-coded bit depth (https://github.com/ultravideo/kvazaar/issues/399).
   // Check whether this matches to the image bit depth.
   // TODO: we should check the bit depth supported by the encoder (like query_input_colorspace2()) and output a warning
@@ -588,22 +604,22 @@ static struct heif_error kvazaar_encode_image(void* encoder_raw, const struct he
     int stride;
     const uint8_t* data = heif_image_get_plane_readonly(image, heif_channel_Y, &stride);
 
-    copy_plane(pic->y, pic->stride, data, stride, input_width, input_height, encoded_width, encoded_height);
+    copy_plane(pic->y, pic->stride, data, stride, input_width, input_height, encoded_width, encoded_height, bit_depth);
   }
   else {
     int stride;
     const uint8_t* data;
 
     data = heif_image_get_plane_readonly(image, heif_channel_Y, &stride);
-    copy_plane(pic->y, pic->stride, data, stride, input_width, input_height, encoded_width, encoded_height);
+    copy_plane(pic->y, pic->stride, data, stride, input_width, input_height, encoded_width, encoded_height, bit_depth);
 
     data = heif_image_get_plane_readonly(image, heif_channel_Cb, &stride);
     copy_plane(pic->u, pic->stride >> chroma_stride_shift, data, stride, input_chroma_width, input_chroma_height,
-               encoded_width >> chroma_stride_shift, encoded_height >> chroma_height_shift);
+               encoded_width >> chroma_stride_shift, encoded_height >> chroma_height_shift, bit_depth_chroma);
 
     data = heif_image_get_plane_readonly(image, heif_channel_Cr, &stride);
     copy_plane(pic->v, pic->stride >> chroma_stride_shift, data, stride, input_chroma_width, input_chroma_height,
-               encoded_width >> chroma_stride_shift, encoded_height >> chroma_height_shift);
+               encoded_width >> chroma_stride_shift, encoded_height >> chroma_height_shift, bit_depth_chroma);
   }
 
   auto uencoder = make_guard(api->encoder_open(config), [api](kvz_encoder* e) { api->encoder_close(e); });