diff --git a/src/imageio/imageio_webp.c b/src/imageio/imageio_webp.c
index 0f245bd33eb2..7ab6655c300b 100644
--- a/src/imageio/imageio_webp.c
+++ b/src/imageio/imageio_webp.c
@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2022-2023 darktable developers.
+    Copyright (C) 2022-2024 darktable developers.
 
     darktable is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -16,8 +16,6 @@
     along with darktable.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <inttypes.h>
-
 #include <webp/decode.h>
 #include <webp/mux.h>
 
@@ -27,9 +25,7 @@
 
 dt_imageio_retval_t dt_imageio_open_webp(dt_image_t *img, const char *filename, dt_mipmap_buffer_t *mbuf)
 {
-  int w, h;
-  WebPMux *mux;
-  WebPData wp_data;
+  int width, height;
   WebPData icc_profile;
 
   FILE *f = g_fopen(filename, "rb");
@@ -55,7 +51,7 @@ dt_imageio_retval_t dt_imageio_open_webp(dt_image_t *img, const char *filename,
   fclose(f);
 
   // WebPGetInfo should tell us the image dimensions needed for darktable image buffer allocation
-  if(!WebPGetInfo(read_buffer, filesize, &w, &h))
+  if(!WebPGetInfo(read_buffer, filesize, &width, &height))
   {
     // If we couldn't get the webp metadata, then the file we're trying to read is most likely in
     // a different format (darktable just trying different loaders until it finds the right one).
@@ -63,8 +59,22 @@ dt_imageio_retval_t dt_imageio_open_webp(dt_image_t *img, const char *filename,
     g_free(read_buffer);
     return DT_IMAGEIO_LOAD_FAILED;
   }
-  img->width = w;
-  img->height = h;
+
+  // The maximum pixel dimensions of a WebP image is 16383 x 16383,
+  // so the number of pixels will never overflow int
+  const int npixels = width * height;
+
+  uint8_t *int_RGBA_buf = dt_alloc_align_uint8(npixels * 4);
+  int_RGBA_buf = WebPDecodeRGBAInto(read_buffer, filesize, int_RGBA_buf, npixels * 4, width * 4);
+  if(!int_RGBA_buf)
+  {
+    g_free(read_buffer);
+    dt_print(DT_DEBUG_ALWAYS,"[webp_open] failed to decode file: %s\n", filename);
+    return DT_IMAGEIO_LOAD_FAILED;
+  }
+
+  img->width = width;
+  img->height = height;
   img->buf_dsc.channels = 4;
   img->buf_dsc.datatype = TYPE_FLOAT;
 
@@ -72,36 +82,30 @@ dt_imageio_retval_t dt_imageio_open_webp(dt_image_t *img, const char *filename,
   if(!mipbuf)
   {
     g_free(read_buffer);
+    dt_free_align(int_RGBA_buf);
     dt_print(DT_DEBUG_ALWAYS, "[webp_open] could not alloc full buffer for image: %s\n", img->filename);
     return DT_IMAGEIO_CACHE_FULL;
   }
 
-  uint8_t *int_RGBA_buf = WebPDecodeRGBA(read_buffer, filesize, &w, &h);
-  if(!int_RGBA_buf)
-  {
-    g_free(read_buffer);
-    dt_print(DT_DEBUG_ALWAYS,"[webp_open] failed to decode file: %s\n", filename);
-    return DT_IMAGEIO_LOAD_FAILED;
-  }
-
-  uint8_t intval;
-  float floatval;
-
 #ifdef _OPENMP
-#pragma omp parallel for private(intval, floatval)
+#pragma omp parallel for default(none) \
+  schedule(static) \
+  dt_omp_firstprivate(npixels, int_RGBA_buf, mipbuf)
 #endif
-  for(int i=0; i < w*h*4; i++)
+  for(int i = 0; i < npixels; i++)
   {
-    intval = *(int_RGBA_buf+i);
-    floatval = intval / 255.f;
-    *(mipbuf+i) = floatval;
+    dt_aligned_pixel_t pix = {0.0f, 0.0f, 0.0f, 0.0f};
+    for_three_channels(c)
+      pix[c] = *(int_RGBA_buf + i * 4 + c) / 255.f;
+    copy_pixel_nontemporal(&mipbuf[i * 4], pix);
   }
 
-  WebPFree(int_RGBA_buf);
+  dt_free_align(int_RGBA_buf);
 
+  WebPData wp_data;
   wp_data.bytes = (uint8_t *)read_buffer;
   wp_data.size = filesize;
-  mux = WebPMuxCreate(&wp_data, 0); // 0 = data will NOT be copied to the mux object
+  WebPMux *mux = WebPMuxCreate(&wp_data, 0); // 0 = data will NOT be copied to the mux object
 
   if(mux)
   {