diff --git a/spec/storage_spec.cr b/spec/storage_spec.cr
index 44bfb5a..ad10de5 100644
--- a/spec/storage_spec.cr
+++ b/spec/storage_spec.cr
@@ -8,9 +8,7 @@ describe Storage do
   end
 
   it "deletes user" do
-    with_storage do |storage|
-      storage.delete_user "admin"
-    end
+    with_storage &.delete_user "admin"
   end
 
   it "creates new user" do
diff --git a/spec/util_spec.cr b/spec/util_spec.cr
index 3ee4aac..27d97c2 100644
--- a/spec/util_spec.cr
+++ b/spec/util_spec.cr
@@ -21,7 +21,7 @@ describe "compare_numerically" do
   it "sorts like the stack exchange post" do
     ary = ["2", "12", "200000", "1000000", "a", "a12", "b2", "text2",
            "text2a", "text2a2", "text2a12", "text2ab", "text12", "text12a"]
-    ary.reverse.sort { |a, b|
+    ary.reverse.sort! { |a, b|
       compare_numerically a, b
     }.should eq ary
   end
@@ -29,7 +29,7 @@ describe "compare_numerically" do
   # https://github.com/hkalexling/Mango/issues/22
   it "handles numbers larger than Int32" do
     ary = ["14410155591588.jpg", "21410155591588.png", "104410155591588.jpg"]
-    ary.reverse.sort { |a, b|
+    ary.reverse.sort! { |a, b|
       compare_numerically a, b
     }.should eq ary
   end
@@ -56,7 +56,7 @@ describe "chapter_sort" do
   it "sorts correctly" do
     ary = ["Vol.1 Ch.01", "Vol.1 Ch.02", "Vol.2 Ch. 2.5", "Ch. 3", "Ch.04"]
     sorter = ChapterSorter.new ary
-    ary.reverse.sort do |a, b|
+    ary.reverse.sort! do |a, b|
       sorter.compare a, b
     end.should eq ary
   end
diff --git a/src/library/entry.cr b/src/library/entry.cr
index cb45895..4ff01ee 100644
--- a/src/library/entry.cr
+++ b/src/library/entry.cr
@@ -86,7 +86,7 @@ class Entry
           SUPPORTED_IMG_TYPES.includes? \
             MIME.from_filename? e.filename
         }
-        .sort { |a, b|
+        .sort! { |a, b|
           compare_numerically a.filename, b.filename
         }
       yield file, entries
diff --git a/src/library/library.cr b/src/library/library.cr
index 7e97e85..e673c19 100644
--- a/src/library/library.cr
+++ b/src/library/library.cr
@@ -63,7 +63,7 @@ class Library
   end
 
   def deep_titles
-    titles + titles.map { |t| t.deep_titles }.flatten
+    titles + titles.flat_map &.deep_titles
   end
 
   def to_json(json : JSON::Builder)
@@ -98,7 +98,7 @@ class Library
       .select { |path| File.directory? path }
       .map { |path| Title.new path, "" }
       .select { |title| !(title.entries.empty? && title.titles.empty?) }
-      .sort { |a, b| a.title <=> b.title }
+      .sort! { |a, b| a.title <=> b.title }
       .tap { |_| @title_ids.clear }
       .each do |title|
         @title_hash[title.id] = title
@@ -114,7 +114,7 @@ class Library
 
   def get_continue_reading_entries(username)
     cr_entries = deep_titles
-      .map { |t| t.get_last_read_entry username }
+      .map(&.get_last_read_entry username)
       # Select elements with type `Entry` from the array and ignore all `Nil`s
       .select(Entry)[0...ENTRIES_IN_HOME_SECTIONS]
       .map { |e|
@@ -150,9 +150,9 @@ class Library
     recently_added = [] of RA
     last_date_added = nil
 
-    titles.map { |t| t.deep_entries_with_date_added }.flatten
-      .select { |e| e[:date_added] > 1.month.ago }
-      .sort { |a, b| b[:date_added] <=> a[:date_added] }
+    titles.flat_map(&.deep_entries_with_date_added)
+      .select(&.[:date_added].> 1.month.ago)
+      .sort! { |a, b| b[:date_added] <=> a[:date_added] }
       .each do |e|
         break if recently_added.size > 12
         last = recently_added.last?
@@ -188,9 +188,9 @@ class Library
     # If we use `deep_titles`, the start reading section might include `Vol. 2`
     #   when the user hasn't started `Vol. 1` yet
     titles
-      .select { |t| t.load_percentage(username) == 0 }
+      .select(&.load_percentage(username).== 0)
       .sample(ENTRIES_IN_HOME_SECTIONS)
-      .shuffle
+      .shuffle!
   end
 
   def thumbnail_generation_progress
@@ -205,7 +205,7 @@ class Library
     end
 
     Logger.info "Starting thumbnail generation"
-    entries = deep_titles.map(&.deep_entries).flatten.reject &.err_msg
+    entries = deep_titles.flat_map(&.deep_entries).reject &.err_msg
     @entries_count = entries.size
     @thumbnails_count = 0
 
diff --git a/src/library/title.cr b/src/library/title.cr
index 4c439e7..a757d42 100644
--- a/src/library/title.cr
+++ b/src/library/title.cr
@@ -44,14 +44,14 @@ class Title
 
     mtimes = [@mtime]
     mtimes += @title_ids.map { |e| Library.default.title_hash[e].mtime }
-    mtimes += @entries.map { |e| e.mtime }
+    mtimes += @entries.map &.mtime
     @mtime = mtimes.max
 
     @title_ids.sort! do |a, b|
       compare_numerically Library.default.title_hash[a].title,
         Library.default.title_hash[b].title
     end
-    sorter = ChapterSorter.new @entries.map { |e| e.title }
+    sorter = ChapterSorter.new @entries.map &.title
     @entries.sort! do |a, b|
       sorter.compare a.title, b.title
     end
@@ -92,12 +92,12 @@ class Title
   # Get all entries, including entries in nested titles
   def deep_entries
     return @entries if title_ids.empty?
-    @entries + titles.map { |t| t.deep_entries }.flatten
+    @entries + titles.flat_map &.deep_entries
   end
 
   def deep_titles
     return [] of Title if titles.empty?
-    titles + titles.map { |t| t.deep_titles }.flatten
+    titles + titles.flat_map &.deep_titles
   end
 
   def parents
@@ -138,7 +138,7 @@ class Title
   end
 
   def get_entry(eid)
-    @entries.find { |e| e.id == eid }
+    @entries.find &.id.== eid
   end
 
   def display_name
@@ -217,29 +217,23 @@ class Title
     @entries.each do |e|
       e.save_progress username, e.pages
     end
-    titles.each do |t|
-      t.read_all username
-    end
+    titles.each &.read_all username
   end
 
   # Set the reading progress of all entries and nested libraries to 0%
   def unread_all(username)
-    @entries.each do |e|
-      e.save_progress username, 0
-    end
-    titles.each do |t|
-      t.unread_all username
-    end
+    @entries.each &.save_progress(username, 0)
+    titles.each &.unread_all username
   end
 
   def deep_read_page_count(username) : Int32
     load_progress_for_all_entries(username).sum +
-      titles.map { |t| t.deep_read_page_count username }.flatten.sum
+      titles.flat_map(&.deep_read_page_count username).sum
   end
 
   def deep_total_page_count : Int32
-    entries.map { |e| e.pages }.sum +
-      titles.map { |t| t.deep_total_page_count }.flatten.sum
+    entries.sum(&.pages) +
+      titles.flat_map(&.deep_total_page_count).sum
   end
 
   def load_percentage(username)
@@ -311,13 +305,13 @@ class Title
       ary = @entries.zip(percentage_ary)
         .sort { |a_tp, b_tp| (a_tp[1] <=> b_tp[1]).or \
           compare_numerically a_tp[0].title, b_tp[0].title }
-        .map { |tp| tp[0] }
+        .map &.[0]
     else
       unless opt.method.auto?
         Logger.warn "Unknown sorting method #{opt.not_nil!.method}. Using " \
                     "Auto instead"
       end
-      sorter = ChapterSorter.new @entries.map { |e| e.title }
+      sorter = ChapterSorter.new @entries.map &.title
       ary = @entries.sort do |a, b|
         sorter.compare(a.title, b.title).or \
           compare_numerically a.title, b.title
@@ -383,13 +377,13 @@ class Title
       {entry: e, date_added: da_ary[i]}
     end
     return zip if title_ids.empty?
-    zip + titles.map { |t| t.deep_entries_with_date_added }.flatten
+    zip + titles.flat_map &.deep_entries_with_date_added
   end
 
   def bulk_progress(action, ids : Array(String), username)
     selected_entries = ids
       .map { |id|
-        @entries.find { |e| e.id == id }
+        @entries.find &.id.==(id)
       }
       .select(Entry)
 
diff --git a/src/mangadex/ext.cr b/src/mangadex/ext.cr
index dfb302c..deb09c8 100644
--- a/src/mangadex/ext.cr
+++ b/src/mangadex/ext.cr
@@ -35,7 +35,7 @@ module MangaDex
   struct Chapter
     def rename(rule : Rename::Rule)
       hash = properties_to_hash %w(id title volume chapter lang_code language)
-      hash["groups"] = groups.map(&.name).join ","
+      hash["groups"] = groups.join(",", &.name)
       rule.render hash
     end
 
diff --git a/src/plugin/plugin.cr b/src/plugin/plugin.cr
index baa77d1..6bedea1 100644
--- a/src/plugin/plugin.cr
+++ b/src/plugin/plugin.cr
@@ -117,7 +117,7 @@ class Plugin
   def initialize(id : String)
     Plugin.build_info_ary
 
-    @info = @@info_ary.find { |i| i.id == id }
+    @info = @@info_ary.find &.id.== id
     if @info.nil?
       raise Error.new "Plugin with ID #{id} not found"
     end
diff --git a/src/queue.cr b/src/queue.cr
index c9f805c..381441b 100644
--- a/src/queue.cr
+++ b/src/queue.cr
@@ -303,12 +303,12 @@ class Queue
   end
 
   def pause
-    @downloaders.each { |d| d.stopped = true }
+    @downloaders.each &.stopped=(true)
     @paused = true
   end
 
   def resume
-    @downloaders.each { |d| d.stopped = false }
+    @downloaders.each &.stopped=(false)
     @paused = false
   end
 
diff --git a/src/rename.cr b/src/rename.cr
index 1fc7693..3e00fdc 100644
--- a/src/rename.cr
+++ b/src/rename.cr
@@ -35,15 +35,15 @@ module Rename
 
   class Group < Base(Pattern | String)
     def render(hash : VHash)
-      return "" if @ary.select(&.is_a? Pattern)
+      return "" if @ary.select(Pattern)
                      .any? &.as(Pattern).render(hash).empty?
-      @ary.map do |e|
+      @ary.join do |e|
         if e.is_a? Pattern
           e.render hash
         else
           e
         end
-      end.join
+      end
     end
   end
 
@@ -129,13 +129,13 @@ module Rename
     end
 
     def render(hash : VHash)
-      str = @ary.map do |e|
+      str = @ary.join do |e|
         if e.is_a? String
           e
         else
           e.render hash
         end
-      end.join.strip
+      end.strip
       post_process str
     end
 
diff --git a/src/routes/api.cr b/src/routes/api.cr
index 34e2857..be7fc1d 100644
--- a/src/routes/api.cr
+++ b/src/routes/api.cr
@@ -339,7 +339,7 @@ struct APIRouter
     }
     post "/api/admin/mangadex/download" do |env|
       begin
-        chapters = env.params.json["chapters"].as(Array).map { |c| c.as_h }
+        chapters = env.params.json["chapters"].as(Array).map &.as_h
         jobs = chapters.map { |chapter|
           Queue::Job.new(
             chapter["id"].as_i64.to_s,
diff --git a/src/routes/main.cr b/src/routes/main.cr
index 6504800..2497c2f 100644
--- a/src/routes/main.cr
+++ b/src/routes/main.cr
@@ -103,7 +103,7 @@ struct MainRouter
         recently_added = Library.default.get_recently_added_entries username
         start_reading = Library.default.get_start_reading_titles username
         titles = Library.default.titles
-        new_user = !titles.any? { |t| t.load_percentage(username) > 0 }
+        new_user = !titles.any? &.load_percentage(username).> 0
         empty_library = titles.size == 0
         layout "home"
       rescue e
diff --git a/src/storage.cr b/src/storage.cr
index 971bba3..39116b9 100644
--- a/src/storage.cr
+++ b/src/storage.cr
@@ -445,7 +445,7 @@ class Storage
           Logger.debug "Marking #{trash_ids.size} entries as unavailable"
         end
         db.exec "update ids set unavailable = 1 where id in " \
-                "(#{trash_ids.map { |i| "'#{i}'" }.join ","})"
+                "(#{trash_ids.join "," { |i| "'#{i}'" }})"
 
         # Detect dangling title IDs
         trash_titles = [] of String
@@ -461,7 +461,7 @@ class Storage
           Logger.debug "Marking #{trash_titles.size} titles as unavailable"
         end
         db.exec "update titles set unavailable = 1 where id in " \
-                "(#{trash_titles.map { |i| "'#{i}'" }.join ","})"
+                "(#{trash_titles.join "," { |i| "'#{i}'" }})"
       end
     end
   end
diff --git a/src/util/chapter_sort.cr b/src/util/chapter_sort.cr
index 44dfb4e..eed7a3e 100644
--- a/src/util/chapter_sort.cr
+++ b/src/util/chapter_sort.cr
@@ -73,7 +73,7 @@ class ChapterSorter
       .select do |key|
         keys[key].count >= str_ary.size / 2
       end
-      .sort do |a_key, b_key|
+      .sort! do |a_key, b_key|
         a = keys[a_key]
         b = keys[b_key]
         # Sort keys by the number of times they appear
diff --git a/src/util/numeric_sort.cr b/src/util/numeric_sort.cr
index 7365a9f..c455b47 100644
--- a/src/util/numeric_sort.cr
+++ b/src/util/numeric_sort.cr
@@ -11,7 +11,7 @@ end
 def split_by_alphanumeric(str)
   arr = [] of String
   str.scan(/([^\d\n\r]*)(\d*)([^\d\n\r]*)/) do |match|
-    arr += match.captures.select { |s| s != "" }
+    arr += match.captures.select &.!= ""
   end
   arr
 end
diff --git a/src/util/util.cr b/src/util/util.cr
index 8903f5e..c4e168a 100644
--- a/src/util/util.cr
+++ b/src/util/util.cr
@@ -114,7 +114,7 @@ class String
   def components_similarity(other : String) : Float64
     s, l = [self, other]
       .map { |str| Path.new(str).parts }
-      .sort_by &.size
+      .sort_by! &.size
 
     match = s.reverse.zip(l.reverse).count { |a, b| a == b }
     match / s.size
diff --git a/src/util/web.cr b/src/util/web.cr
index 67227c7..12459e5 100644
--- a/src/util/web.cr
+++ b/src/util/web.cr
@@ -72,7 +72,7 @@ def redirect(env, path)
 end
 
 def hash_to_query(hash)
-  hash.map { |k, v| "#{k}=#{v}" }.join("&")
+  hash.join "&" { |k, v| "#{k}=#{v}" }
 end
 
 def request_path_startswith(env, ary)