diff --git a/app/controllers/iiif_controller.rb b/app/controllers/iiif_controller.rb
index 28506185..43950aa3 100644
--- a/app/controllers/iiif_controller.rb
+++ b/app/controllers/iiif_controller.rb
@@ -4,6 +4,7 @@
 # API for delivering IIIF-compatible images and image tiles
 class IiifController < ApplicationController
   before_action :ensure_valid_identifier
+  before_action :ensure_identifier_has_extension
   before_action :add_iiif_profile_header
 
   # Follow the interface of Riiif
@@ -137,7 +138,7 @@ def transformation
   end
 
   def stacks_identifier
-    @stacks_identifier ||= StacksIdentifier.new(escaped_identifier.sub(/^degraded_/, '') + '.jp2')
+    @stacks_identifier ||= StacksIdentifier.new(escaped_identifier.sub(/^degraded_/, ''))
   end
 
   def canonical_params
@@ -168,6 +169,14 @@ def degraded?
       !can?(:download, current_image) && current_image.readable_by?(stanford_generic_user)
   end
 
+  # Stacks used to allow requesting images without an extension. However this was
+  # different than how requests for media or file downloads worked.  Now we prefer the
+  # full file name for consistency across all endpoints.
+  def ensure_identifier_has_extension
+    return if stacks_identifier.has_file_name_extension?
+    redirect_to identifier: stacks_identifier.to_s + '.jp2' # halts the request cycle
+  end
+
   def ensure_valid_identifier
     raise ActionController::RoutingError, "invalid identifer" unless stacks_identifier.valid?
   end
diff --git a/app/models/stacks_identifier.rb b/app/models/stacks_identifier.rb
index 0a753f68..a2c4971f 100644
--- a/app/models/stacks_identifier.rb
+++ b/app/models/stacks_identifier.rb
@@ -32,6 +32,10 @@ def file_name_without_ext
     File.basename(file_name, '.*')
   end
 
+  def has_file_name_extension?
+    File.extname(file_name).present?
+  end
+
   def treeified_path
     File.join(druid_parts[1..4], file_name)
   end
diff --git a/config/routes.rb b/config/routes.rb
index f41a6b4a..f99fb8e3 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -22,7 +22,7 @@
 
   constraints identifier: %r{[^/]+}, size: %r{[^/]+} do
     get '/image/iiif/:identifier', to: redirect('/image/iiif/%{identifier}/info.json', status: 303), as: :iiif_base
-    get '/image/iiif/:identifier/:region/:size/:rotation/:quality' => 'iiif#show', as: :iiif
+    get '/image/iiif/:identifier/:region/:size/:rotation/:quality.:format' => 'iiif#show', as: :iiif
     get '/image/iiif/:identifier/info.json' => 'iiif#metadata', as: :iiif_metadata
     match '/image/iiif/:identifier/info.json' => 'iiif#metadata_options', via: [:options]
     get '/image/iiif/app/:identifier/:region/:size/:rotation/:quality' => 'webauth#login_iiif'
diff --git a/spec/controllers/iiif_controller_spec.rb b/spec/controllers/iiif_controller_spec.rb
index 52fcdeaa..0c672a9c 100644
--- a/spec/controllers/iiif_controller_spec.rb
+++ b/spec/controllers/iiif_controller_spec.rb
@@ -2,7 +2,7 @@
 
 RSpec.describe IiifController do
   describe '#show' do
-    let(:identifier) { 'nr349ct7889%2Fnr349ct7889_00_0001' }
+    let(:identifier) { 'nr349ct7889%2Fnr349ct7889_00_0001.jp2' }
     let(:image_response) { StringIO.new }
     let(:projection) { instance_double(Projection, response: image_response, valid?: true) }
     let(:image) do
@@ -51,12 +51,22 @@
       end
     end
 
+    context "when the file name doesn't have an extension" do
+      let(:identifier) { 'nr349ct7889%2Fnr349ct7889_00_0001' }
+      it 'redirects to the url with an extension' do
+        subject
+        expect(response).to redirect_to(
+          'http://test.host/image/iiif/nr349ct7889%252Fnr349ct7889_00_0001.jp2/0,640,2552,2552/100,100/0/default.jpg'
+        )
+      end
+    end
+
     it 'loads the image' do
       subject
       expect(assigns(:image)).to eq image
       expect(StacksImage).to have_received(:new).with(
         id: StacksIdentifier.new(druid: "nr349ct7889", file_name: 'nr349ct7889_00_0001.jp2'),
-        canonical_url: "http://test.host/image/iiif/nr349ct7889%252Fnr349ct7889_00_0001"
+        canonical_url: "http://test.host/image/iiif/nr349ct7889%252Fnr349ct7889_00_0001.jp2"
       )
     end
 
@@ -93,41 +103,55 @@
   end
 
   describe '#metadata' do
-    let(:image) do
-      instance_double(StacksImage,
-                      valid?: true,
-                      exist?: true,
-                      etag: nil,
-                      mtime: nil)
+    context "when the file name doesn't have an extension" do
+      let(:identifier) { 'nr349ct7889%2Fnr349ct7889_00_0001' }
+
+      it 'redirects to the url with an extension' do
+        get :metadata, params: { identifier: identifier, format: :json }
+        expect(response).to redirect_to(
+          'http://test.host/image/iiif/nr349ct7889%252Fnr349ct7889_00_0001.jp2/info.json'
+        )
+      end
     end
-    let(:anon_user) { instance_double(User) }
 
-    before do
-      # for the cache headers
-      allow(controller).to receive(:anonymous_locatable_user).and_return(anon_user)
-      allow(image).to receive(:accessable_by?).with(anon_user).and_return(false)
-      # for info.json generation
-      allow(controller.send(:anonymous_ability)).to receive(:can?).with(:download, image).and_return(false)
-      # for current_image
-      allow(controller).to receive(:can?).with(:download, image).and_return(true)
-      # for degraded?
-      allow(controller).to receive(:can?).with(:access, image).and_return(true)
-      # In the metadata method itself
-      allow(controller).to receive(:authorize!).with(:read_metadata, image).and_return(true)
-
-      allow(StacksImage).to receive(:new).and_return(image)
-
-      allow(IiifInfoService).to receive(:info)
-        .with(image, false, controller)
-        .and_return(height: '999')
-    end
+    context "on the happy path" do
+      let(:identifier) { 'nr349ct7889%2Fnr349ct7889_00_0001.jp2' }
+      let(:image) do
+        instance_double(StacksImage,
+                        valid?: true,
+                        exist?: true,
+                        etag: nil,
+                        mtime: nil)
+      end
+      let(:anon_user) { instance_double(User) }
+
+      before do
+        # for the cache headers
+        allow(controller).to receive(:anonymous_locatable_user).and_return(anon_user)
+        allow(image).to receive(:accessable_by?).with(anon_user).and_return(false)
+        # for info.json generation
+        allow(controller.send(:anonymous_ability)).to receive(:can?).with(:download, image).and_return(false)
+        # for current_image
+        allow(controller).to receive(:can?).with(:download, image).and_return(true)
+        # for degraded?
+        allow(controller).to receive(:can?).with(:access, image).and_return(true)
+        # In the metadata method itself
+        allow(controller).to receive(:authorize!).with(:read_metadata, image).and_return(true)
+
+        allow(StacksImage).to receive(:new).and_return(image)
+
+        allow(IiifInfoService).to receive(:info)
+          .with(image, false, controller)
+          .and_return(height: '999')
+      end
 
-    it 'provides iiif info.json responses' do
-      get :metadata, params: { identifier: 'nr349ct7889%2Fnr349ct7889_00_0001', format: :json }
-      expect(controller.content_type).to eq 'application/json'
-      expect(response).to be_successful
-      expect(controller.response_body.first).to eq "{\n  \"height\": \"999\"\n}"
-      expect(controller.headers['Link']).to eq '<http://iiif.io/api/image/2/level2.json>;rel="profile"'
+      it 'provides iiif info.json responses' do
+        get :metadata, params: { identifier: identifier, format: :json }
+        expect(controller.content_type).to eq 'application/json'
+        expect(response).to be_successful
+        expect(controller.response_body.first).to eq "{\n  \"height\": \"999\"\n}"
+        expect(controller.headers['Link']).to eq '<http://iiif.io/api/image/2/level2.json>;rel="profile"'
+      end
     end
   end
 end
diff --git a/spec/requests/iiif_auth_request_spec.rb b/spec/requests/iiif_auth_request_spec.rb
index 24d0892b..eaf76fb2 100644
--- a/spec/requests/iiif_auth_request_spec.rb
+++ b/spec/requests/iiif_auth_request_spec.rb
@@ -9,7 +9,7 @@
   let(:user_webauth_stanford_no_loc) { User.new(webauth_user: true, ldap_groups: %w(stanford:stanford)) }
   let(:user_webauth_stanford_loc) { User.new(webauth_user: true, ldap_groups: %w(stanford:stanford), ip_address: allowed_loc) }
   let(:user_webauth_no_stanford_loc) { User.new(webauth_user: true, ip_address: allowed_loc) }
-  let(:identifier) { StacksIdentifier.new('nr349ct7889%2Fnr349ct7889_00_0001') }
+  let(:identifier) { StacksIdentifier.new('nr349ct7889%2Fnr349ct7889_00_0001.jp2') }
   let(:region) { '0,640,2552,2552' }
   let(:size) { '100,100' }
   let(:rotation) { '0' }
@@ -17,7 +17,7 @@
   let(:format) { 'jpg' }
   let(:params_hash) { { id: identifier, transformation: transformation } }
   let(:transformation) { IIIF::Image::Transformation.new region: region, size: size, rotation: rotation, quality: quality, format: format }
-  let(:path) { "/stacks/nr/349/ct/7889/nr349ct7889_00_0001" }
+  let(:path) { "/stacks/nr/349/ct/7889/nr349ct7889_00_0001.jp2" }
   let(:perms) { nil }
 
   before(:each) do
diff --git a/spec/requests/iiif_spec.rb b/spec/requests/iiif_spec.rb
index 1805a1b5..35721eea 100644
--- a/spec/requests/iiif_spec.rb
+++ b/spec/requests/iiif_spec.rb
@@ -38,7 +38,7 @@
   end
 
   it 'handles JSON-LD requests' do
-    get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001/info.json', headers: { HTTP_ACCEPT: 'application/ld+json' }
+    get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001.jp2/info.json', headers: { HTTP_ACCEPT: 'application/ld+json' }
 
     expect(response.content_type).to eq 'application/ld+json'
     json = JSON.parse(response.body)
@@ -51,9 +51,9 @@
     end
 
     it 'redirects requests to the degraded info.json' do
-      get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001/info.json'
+      get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001.jp2/info.json'
       expect(response).to have_http_status :redirect
-      expect(response).to redirect_to('/image/iiif/degraded_nr349ct7889%252Fnr349ct7889_00_0001/info.json')
+      expect(response).to redirect_to('/image/iiif/degraded_nr349ct7889%252Fnr349ct7889_00_0001.jp2/info.json')
       expect(response.headers['Cache-Control']).to match(/max-age=0/)
     end
 
@@ -71,7 +71,7 @@
       stub_rights_xml(world_no_download_xml)
     end
     it 'serves up regular info.json (no degraded)' do
-      get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001/info.json'
+      get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001.jp2/info.json'
       expect(response).to have_http_status :ok
     end
   end
@@ -81,9 +81,9 @@
       stub_rights_xml(stanford_only_no_download_xml)
     end
     it 'redirects to degraded version' do
-      get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001/info.json'
+      get '/image/iiif/nr349ct7889%2Fnr349ct7889_00_0001.jp2/info.json'
       expect(response).to have_http_status :redirect
-      expect(response).to redirect_to('/image/iiif/degraded_nr349ct7889%252Fnr349ct7889_00_0001/info.json')
+      expect(response).to redirect_to('/image/iiif/degraded_nr349ct7889%252Fnr349ct7889_00_0001.jp2/info.json')
     end
   end
 end
diff --git a/spec/requests/remote_iiif_image_delivery_spec.rb b/spec/requests/remote_iiif_image_delivery_spec.rb
index 1ba7c218..bd38e524 100644
--- a/spec/requests/remote_iiif_image_delivery_spec.rb
+++ b/spec/requests/remote_iiif_image_delivery_spec.rb
@@ -27,7 +27,7 @@
   end
 
   it 'returns an image' do
-    get '/image/iiif/nr349ct7889%2Fimage/full/max/0/default.jpg'
+    get '/image/iiif/nr349ct7889%2Fimage.jp2/full/max/0/default.jpg'
     expect(response.body).to eq 'image contents'
   end
 end