diff --git a/app/assets/javascripts/common.js b/app/assets/javascripts/common.js
index cbec48d0b..2b345a26d 100644
--- a/app/assets/javascripts/common.js
+++ b/app/assets/javascripts/common.js
@@ -39,6 +39,11 @@ $(function() {
       location.reload();
     });
   });
+
+  // triggered by rails when a `link_to ..., remote: true` call fails.
+  $(document).on("ajax:error", function (event, xhr, status, error) {
+    Danbooru.error("Error: " + xhr.status + " " + xhr.statusText);
+  });
 });
 
 var Danbooru = {};
diff --git a/app/controllers/iqdb_queries_controller.rb b/app/controllers/iqdb_queries_controller.rb
index 62a9b93a5..ee865c974 100644
--- a/app/controllers/iqdb_queries_controller.rb
+++ b/app/controllers/iqdb_queries_controller.rb
@@ -3,31 +3,16 @@ class IqdbQueriesController < ApplicationController
   respond_to :html, :json, :xml
 
   def show
-    server_check
-    if params[:url]
-      create_by_url
-      respond_with(@results) do |fmt|
-        fmt.html { render :layout => false, :action => "create_by_url" }
-      end
-    elsif params[:post_id]
-      create_by_post
-      respond_with(@results) do |fmt|
-        fmt.js { render :layout => false, :action => "create_by_post" }
-      end
-    else
-      render :nothing => true, :status => 422
+    @results = find_similar
+
+    respond_with(@results) do |fmt|
+      fmt.html { render :layout => false, :action => "create_by_url" }
+      fmt.js { render :layout => false, :action => "create_by_post" }
     end
   end
 
   def check
-    server_check
-    if params[:url].present?
-      create_by_url
-    elsif params[:post_id].present?
-      create_by_post
-    else
-      @results = []
-    end
+    @results = find_similar
     respond_with(@results)
   end
 
@@ -35,22 +20,10 @@ class IqdbQueriesController < ApplicationController
   alias_method :create, :show
 
 protected
-  def server_check
-    if !Danbooru.config.iqdbs_server
-      raise NotImplementedError.new("the IQDBs service isn't configured. Similarity searches are not available.")
-    end
-  end
+  def find_similar
+    return [] if params[:url].blank? && params[:post_id].blank?
 
-  def create_by_url
-    @download = Iqdb::Download.new(params[:url])
-    @download.find_similar
-    @results = @download.matches
-  end
-
-  def create_by_post
-    @post = Post.find(params[:post_id])
-    @download = Iqdb::Download.new(@post.preview_file_url)
-    @download.find_similar
-    @results = @download.matches
+    params[:url] = Post.find(params[:post_id]).preview_file_url if params[:post_id].present?
+    Iqdb::Download.find_similar(params[:url])
   end
 end
diff --git a/app/logical/iqdb/download.rb b/app/logical/iqdb/download.rb
index e77f4d1eb..bdb74ae55 100644
--- a/app/logical/iqdb/download.rb
+++ b/app/logical/iqdb/download.rb
@@ -1,12 +1,12 @@
 module Iqdb
   class Download
-    attr_reader :source, :download, :matches
+    class Error < StandardError; end
 
-    def initialize(source)
-      @source = source
+    def self.enabled?
+      Danbooru.config.iqdbs_server.present? && Danbooru.config.iqdbs_auth_key.present?
     end
 
-    def get_referer(url)
+    def self.get_referer(url)
       headers = {}
       datums = {}
 
@@ -17,37 +17,33 @@ module Iqdb
       [url, headers["Referer"]]
     end
 
-    def find_similar
-      if Danbooru.config.iqdbs_server
-        url, ref = get_referer(source)
-        params = {
-          "key" => Danbooru.config.iqdbs_auth_key,
-          "url" => url,
-          "ref" => ref
-        }
-        uri = URI.parse("#{Danbooru.config.iqdbs_server}/similar")
-        uri.query = URI.encode_www_form(params)
+    def self.find_similar(source)
+      raise NotImplementedError, "the IQDBs service isn't configured. Similarity searches are not available." unless enabled?
 
-        resp = HTTParty.get(uri, Danbooru.config.httparty_options)
-        if resp.success?
-          json = JSON.parse(resp.body)
-          if json.is_a?(Array)
-            post_ids = json.map { |match| match["post_id"] }
-            posts = Post.find(post_ids)
+      url, ref = get_referer(source)
+      params = {
+        "key" => Danbooru.config.iqdbs_auth_key,
+        "url" => url,
+        "ref" => ref
+      }
+      uri = URI.parse("#{Danbooru.config.iqdbs_server}/similar")
+      uri.query = URI.encode_www_form(params)
 
-            @matches = json.map do |match|
-              post = posts.find { |post| post.id == match["post_id"] }
-              match.with_indifferent_access.merge({ post: post })
-            end
-          else
-            @matches = []
-          end
-        else
-          raise "HTTP error code: #{resp.code} #{resp.message}"
-        end
-      else
-        raise NotImplementedError
+      resp = HTTParty.get(uri, Danbooru.config.httparty_options)
+      raise "HTTP error code: #{resp.code} #{resp.message}" unless resp.success?
+
+      json = JSON.parse(resp.body)
+      raise "IQDB error: #{json["error"]}" unless json.is_a?(Array)
+
+      post_ids = json.map { |match| match["post_id"] }
+      posts = Post.find(post_ids)
+
+      json.map do |match|
+        post = posts.find { |post| post.id == match["post_id"] }
+        match.with_indifferent_access.merge({ post: post })
       end
+    rescue => e
+      raise Error, { message: e.message, iqdb_response: json }
     end
   end
 end