diff --git a/config/runtime.exs b/config/runtime.exs
index b4e6dc5f1..fb2372ea6 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -8,6 +8,6 @@ end
 rootpath = System.get_env("RELEASE_ROOT", rootdefault)
 config :ejabberd,
   file: Path.join(rootpath, "conf/ejabberd.yml"),
-  log_path: Path.join(rootpath, 'logs/ejabberd.log')
+  log_path: Path.join(rootpath, "logs/ejabberd.log")
 config :mnesia,
-  dir: Path.join(rootpath, 'database/')
+  dir: Path.join(rootpath, "database/")
diff --git a/lib/ejabberd/config/ejabberd_module.ex b/lib/ejabberd/config/ejabberd_module.ex
index 6a74fe460..57fd8303c 100644
--- a/lib/ejabberd/config/ejabberd_module.ex
+++ b/lib/ejabberd/config/ejabberd_module.ex
@@ -60,7 +60,7 @@ defmodule Ejabberd.Config.EjabberdModule do
   defp fetch_and_store_repo_source_if_not_exists(path, repo) do
     unless File.exists?(path) do
       IO.puts "[info] Fetching: #{repo}"
-      :os.cmd('git clone #{repo} #{path}')
+      :os.cmd(~c"git clone #{repo} #{path}")
     end
   end
 
diff --git a/lib/mod_presence_demo.ex b/lib/mod_presence_demo.ex
index f41a53a31..c5be5bba5 100644
--- a/lib/mod_presence_demo.ex
+++ b/lib/mod_presence_demo.ex
@@ -2,19 +2,19 @@ defmodule ModPresenceDemo do
   use Ejabberd.Module
 
   def start(host, _opts) do
-    info('Starting ejabberd module Presence Demo')
+    info("Starting ejabberd module Presence Demo")
     Ejabberd.Hooks.add(:set_presence_hook, host, __MODULE__, :on_presence, 50)
     :ok
   end
 
   def stop(host) do
-    info('Stopping ejabberd module Presence Demo')
+    info("Stopping ejabberd module Presence Demo")
     Ejabberd.Hooks.delete(:set_presence_hook, host, __MODULE__, :on_presence, 50)
     :ok
   end
 
   def on_presence(user, _server, _resource, _packet) do
-    info('Receive presence for #{user}')
+    info("Receive presence for #{user}")
     :none
   end
 
@@ -27,7 +27,7 @@ defmodule ModPresenceDemo do
   end
 
   def mod_doc() do
-    %{:desc => 'This is just a demonstration.'}
+    %{:desc => "This is just a demonstration."}
   end
 
 end
diff --git a/mix.exs b/mix.exs
index cc3c1c55b..faf559446 100644
--- a/mix.exs
+++ b/mix.exs
@@ -23,11 +23,11 @@ defmodule Ejabberd.MixProject do
   def version do
     case config(:vsn) do
       :false -> "0.0.0" # ./configure wasn't run: vars.config not created
-      '0.0' -> "0.0.0" # the full git repository wasn't downloaded
-      'latest.0' -> "0.0.0" # running 'docker-ejabberd/ecs/build.sh latest'
+      ~c"0.0" -> "0.0.0" # the full git repository wasn't downloaded
+      ~c"latest.0" -> "0.0.0" # running 'docker-ejabberd/ecs/build.sh latest'
       [_, _, ?., _, _] = x ->
         head = String.replace(:erlang.list_to_binary(x), ~r/\.0+([0-9])/, ".\\1")
-        <<head::binary, ".0">>
+        "#{head}.0"
       vsn -> String.replace(:erlang.list_to_binary(vsn), ~r/\.0+([0-9])/, ".\\1")
     end
   end
@@ -72,16 +72,16 @@ defmodule Ejabberd.MixProject do
     result = [{:d, :ELIXIR_ENABLED}] ++
              cond_options() ++
              Enum.map(includes, fn (path) -> {:i, path} end) ++
-             if_version_above('20', [{:d, :DEPRECATED_GET_STACKTRACE}]) ++
-             if_version_above('20', [{:d, :HAVE_URI_STRING}]) ++
-             if_version_above('20', [{:d, :HAVE_ERL_ERROR}]) ++
-             if_version_below('21', [{:d, :USE_OLD_HTTP_URI}]) ++
-             if_version_below('22', [{:d, :LAGER}]) ++
-             if_version_below('21', [{:d, :NO_CUSTOMIZE_HOSTNAME_CHECK}]) ++
-             if_version_below('23', [{:d, :USE_OLD_CRYPTO_HMAC}]) ++
-             if_version_below('23', [{:d, :USE_OLD_PG2}]) ++
-             if_version_below('24', [{:d, :COMPILER_REPORTS_ONLY_LINES}]) ++
-             if_version_below('24', [{:d, :SYSTOOLS_APP_DEF_WITHOUT_OPTIONAL}])
+             if_version_above(~c"20", [{:d, :DEPRECATED_GET_STACKTRACE}]) ++
+             if_version_above(~c"20", [{:d, :HAVE_URI_STRING}]) ++
+             if_version_above(~c"20", [{:d, :HAVE_ERL_ERROR}]) ++
+             if_version_below(~c"21", [{:d, :USE_OLD_HTTP_URI}]) ++
+             if_version_below(~c"22", [{:d, :LAGER}]) ++
+             if_version_below(~c"21", [{:d, :NO_CUSTOMIZE_HOSTNAME_CHECK}]) ++
+             if_version_below(~c"23", [{:d, :USE_OLD_CRYPTO_HMAC}]) ++
+             if_version_below(~c"23", [{:d, :USE_OLD_PG2}]) ++
+             if_version_below(~c"24", [{:d, :COMPILER_REPORTS_ONLY_LINES}]) ++
+             if_version_below(~c"24", [{:d, :SYSTOOLS_APP_DEF_WITHOUT_OPTIONAL}])
     defines = for {:d, value} <- result, do: {:d, value}
     result ++ [{:d, :ALL_DEFS, defines}]
   end
@@ -136,7 +136,7 @@ defmodule Ejabberd.MixProject do
                          {config(:redis), {:eredis, "~> 1.2.0"}},
                          {config(:sip), {:esip, "~> 1.0"}},
                          {config(:zlib), {:ezlib, "~> 1.0"}},
-                         {if_version_below('22', true), {:lager, "~> 3.9.1"}},
+                         {if_version_below(~c"22", true), {:lager, "~> 3.9.1"}},
                          {config(:lua), {:luerl, "~> 1.0"}},
                          {config(:mysql), {:p1_mysql, git: "https://github.com/processone/p1_mysql.git", ref: "f685408b910c425b9905d4ddcdbedba717a5b48c"}},
                          {config(:pgsql), {:p1_pgsql, "~> 1.1"}},
@@ -154,7 +154,7 @@ defmodule Ejabberd.MixProject do
     for {:true, app} <- [{config(:pam), :epam},
                          {config(:lua), :luerl},
                          {config(:redis), :eredis},
-                         {if_version_below('22', true), :lager},
+                         {if_version_below(~c"22", true), :lager},
                          {config(:mysql), :p1_mysql},
                          {config(:sip), :esip},
                          {config(:odbc), :odbc},
@@ -214,7 +214,7 @@ defmodule Ejabberd.MixProject do
           _ -> :ok
         end
         case Version.match?(System.version(), "< 1.11.4")
-          and :erlang.system_info(:otp_release) > '23' do
+          and :erlang.system_info(:otp_release) > ~c"23" do
           true ->
             IO.puts("ERROR: To build releases with Elixir lower than 1.11.4, Erlang/OTP lower than 24 is required.")
           _ -> :ok