diff --git a/src/common/mipmap_cache.c b/src/common/mipmap_cache.c
index 4a445e3c15fb..58c282d5cef3 100644
--- a/src/common/mipmap_cache.c
+++ b/src/common/mipmap_cache.c
@@ -1464,7 +1464,7 @@ static void _init_8(uint8_t *buf,
       uint8_t *tmp = 0;
       int32_t thumb_width, thumb_height;
       res = dt_imageio_large_thumbnail(filename, &tmp, &thumb_width, &thumb_height, color_space);
-      if(!res)
+      if(res)
       {
         // if the thumbnail is not large enough, we compute one
         const dt_image_t *img2 = dt_image_cache_get(darktable.image_cache, imgid, 'r');
@@ -1528,10 +1528,11 @@ static void _init_8(uint8_t *buf,
     // export with flags: ignore exif(don't load from disk), don't
     // swap byte order, don't do hq processing, no upscaling and
     // signal we want thumbnail export
-    res = dt_imageio_export_with_flags(imgid, "unused", &format, (dt_imageio_module_data_t *)&dat, TRUE, FALSE, FALSE,
-                                       FALSE, FALSE, TRUE, NULL, FALSE, FALSE, DT_COLORSPACE_NONE, NULL, DT_INTENT_LAST, NULL,
-                                       NULL, 1, 1, NULL, -1);
-    if(!res)
+    res = dt_imageio_export_with_flags
+      (imgid, "unused", &format, (dt_imageio_module_data_t *)&dat, TRUE, FALSE, FALSE,
+       FALSE, FALSE, TRUE, NULL, FALSE, FALSE, DT_COLORSPACE_NONE, NULL, DT_INTENT_LAST,
+       NULL, NULL, 1, 1, NULL, -1);
+    if(res)
     {
       dt_print(DT_DEBUG_CACHE,
                "[mipmap_cache] generate mip %d for ID=%d from scratch\n",
@@ -1548,7 +1549,7 @@ static void _init_8(uint8_t *buf,
   // dat.head.width, dat.head.height);
 
   // any errors?
-  if(res)
+  if(!res)
   {
     // dt_print(DT_DEBUG_ALWAYS, "[mipmap_cache] could not process thumbnail!\n");
     *width = *height = 0;
diff --git a/src/dtgtk/thumbnail.c b/src/dtgtk/thumbnail.c
index 0beef73129af..254ef9f6ae5f 100644
--- a/src/dtgtk/thumbnail.c
+++ b/src/dtgtk/thumbnail.c
@@ -795,9 +795,9 @@ static gboolean _event_image_draw(GtkWidget *widget,
       char path[PATH_MAX] = { 0 };
       gboolean from_cache = TRUE;
       dt_image_full_path(thumb->imgid, path, sizeof(path), &from_cache);
-      if(!dt_imageio_large_thumbnail(path, &full_res_thumb,
-                                     &full_res_thumb_wd, &full_res_thumb_ht,
-                                     &color_space))
+      if(dt_imageio_large_thumbnail(path, &full_res_thumb,
+                                    &full_res_thumb_wd, &full_res_thumb_ht,
+                                    &color_space))
       {
         // we look for focus areas
         dt_focus_cluster_t full_res_focus[49];
diff --git a/src/imageio/imageio.c b/src/imageio/imageio.c
index 4b1b725ed482..ebd15435e231 100644
--- a/src/imageio/imageio.c
+++ b/src/imageio/imageio.c
@@ -153,7 +153,7 @@ gboolean dt_imageio_large_thumbnail(const char *filename,
                                     int32_t *height,
                                     dt_colorspaces_color_profile_type_t *color_space)
 {
-  int res = TRUE;
+  int res = FALSE;
 
   uint8_t *buf = NULL;
   char *mime_type = NULL;
@@ -185,7 +185,7 @@ gboolean dt_imageio_large_thumbnail(const char *filename,
       goto error;
     }
 
-    res = FALSE;
+    res = TRUE;
   }
   else
   {
@@ -236,13 +236,13 @@ gboolean dt_imageio_large_thumbnail(const char *filename,
       }
     }
 
-    res = FALSE;
+    res = TRUE;
 
   error_gm:
     if(image) DestroyImage(image);
     if(image_info) DestroyImageInfo(image_info);
     DestroyExceptionInfo(&exception);
-    if(res) goto error;
+    if(!res) goto error;
 #elif defined HAVE_IMAGEMAGICK
     MagickWand *image = NULL;
     MagickBooleanType mret;
@@ -287,11 +287,11 @@ gboolean dt_imageio_large_thumbnail(const char *filename,
       goto error_im;
     }
 
-    res = FALSE;
+    res = TRUE;
 
 error_im:
     DestroyMagickWand(image);
-    if(res) goto error;
+    if(!res) goto error;
 #else
     dt_print(DT_DEBUG_ALWAYS,
       "[dt_imageio_large_thumbnail] error: The thumbnail image is not in "
@@ -301,7 +301,7 @@ gboolean dt_imageio_large_thumbnail(const char *filename,
 #endif
   }
 
-  if(res)
+  if(!res)
   {
     dt_print(DT_DEBUG_ALWAYS,
              "[dt_imageio_large_thumbnail] error: Not a supported thumbnail "
@@ -706,9 +706,9 @@ gboolean dt_imageio_export(const dt_imgid_t imgid,
 {
   if(strcmp(format->mime(format_params), "x-copy") == 0)
     /* This is a just a copy, skip process and just export */
-    return (format->write_image(format_params, filename, NULL, icc_type,
+    return format->write_image(format_params, filename, NULL, icc_type,
                                icc_filename, NULL, 0, imgid, num, total, NULL,
-                               export_masks)) != 0;
+                               export_masks);
   else
   {
     const gboolean is_scaling =