diff --git a/app/models/alchemy/picture.rb b/app/models/alchemy/picture.rb
index 6acffe40b9..7b3e685735 100644
--- a/app/models/alchemy/picture.rb
+++ b/app/models/alchemy/picture.rb
@@ -205,7 +205,7 @@ def thumbnail_url(size: "160x120", quality: THUMBNAIL_QUALITY)
 
       url(
         flatten: true,
-        format: "webp",
+        format: image_file_format || "jpg",
         quality: quality,
         size: size
       )
diff --git a/app/models/concerns/alchemy/picture_thumbnails.rb b/app/models/concerns/alchemy/picture_thumbnails.rb
index 76ace9a392..16bc25f29a 100644
--- a/app/models/concerns/alchemy/picture_thumbnails.rb
+++ b/app/models/concerns/alchemy/picture_thumbnails.rb
@@ -84,7 +84,7 @@ def thumbnail_url_options
         crop_from: crop && crop_from.presence || default_crop_from&.join("x"),
         crop_size: crop && crop_size.presence || default_crop_size&.join("x"),
         flatten: true,
-        format: "webp",
+        format: picture&.image_file_format || "jpg",
         quality: Alchemy::Picture::THUMBNAIL_QUALITY
       }
     end
diff --git a/lib/alchemy/test_support/having_picture_thumbnails_examples.rb b/lib/alchemy/test_support/having_picture_thumbnails_examples.rb
index 5165cb22a1..737e3d93ae 100644
--- a/lib/alchemy/test_support/having_picture_thumbnails_examples.rb
+++ b/lib/alchemy/test_support/having_picture_thumbnails_examples.rb
@@ -203,8 +203,8 @@
       allow(record).to receive(:settings) { settings }
     end
 
-    it "includes webp file format." do
-      expect(thumbnail_url).to match(/\.webp/)
+    it "includes the image's original file format." do
+      expect(thumbnail_url).to match(/\.png/)
     end
 
     it "flattens the image." do
@@ -305,8 +305,8 @@
         create(:alchemy_picture)
       end
 
-      it "uses webp image format." do
-        expect(thumbnail_url_options[:format]).to eq("webp")
+      it "includes the image's original file format." do
+        expect(thumbnail_url_options[:format]).to eq("png")
       end
 
       it "flattens the image." do
@@ -381,7 +381,7 @@
           crop_from: nil,
           crop_size: nil,
           flatten: true,
-          format: "webp",
+          format: "jpg",
           quality: Alchemy::Picture::THUMBNAIL_QUALITY,
           size: "160x120"
         )
@@ -401,7 +401,7 @@
             crop_from: nil,
             crop_size: nil,
             flatten: true,
-            format: "webp",
+            format: "jpg",
             quality: Alchemy::Picture::THUMBNAIL_QUALITY,
             size: "160x120"
           )
diff --git a/spec/models/alchemy/picture_spec.rb b/spec/models/alchemy/picture_spec.rb
index 9c0b0dd70c..d3c6c91f4e 100644
--- a/spec/models/alchemy/picture_spec.rb
+++ b/spec/models/alchemy/picture_spec.rb
@@ -334,7 +334,7 @@ module Alchemy
         it "returns the url to the thumbnail" do
           expect(picture).to receive(:url).with(
             flatten: true,
-            format: "webp",
+            format: "png",
             quality: Alchemy::Picture::THUMBNAIL_QUALITY,
             size: "160x120"
           )
@@ -347,7 +347,7 @@ module Alchemy
           it "returns the url to the thumbnail" do
             expect(picture).to receive(:url).with(
               flatten: true,
-              format: "webp",
+              format: "png",
               quality: Alchemy::Picture::THUMBNAIL_QUALITY,
               size: "800x600"
             )
@@ -361,7 +361,7 @@ module Alchemy
           it "returns the url to the thumbnail" do
             expect(picture).to receive(:url).with(
               flatten: true,
-              format: "webp",
+              format: "png",
               quality: 50,
               size: "160x120"
             )