diff --git a/lib/launchy.rb b/lib/launchy.rb
index d7fe262..8e9d73d 100644
--- a/lib/launchy.rb
+++ b/lib/launchy.rb
@@ -86,15 +86,15 @@ def reset_global_options
       Launchy.application = nil
       Launchy.host_os     = nil
       Launchy.dry_run     = false
-      Launchy.path        = ENV["PATH"]
+      Launchy.path        = ENV.fetch("PATH", nil)
     end
 
     def extract_global_options(options)
       leftover = options.dup
-      Launchy.debug        = leftover.delete(:debug) || ENV["LAUNCHY_DEBUG"]
-      Launchy.application  = leftover.delete(:application) || ENV["LAUNCHY_APPLICATION"]
-      Launchy.host_os      = leftover.delete(:host_os) || ENV["LAUNCHY_HOST_OS"]
-      Launchy.dry_run      = leftover.delete(:dry_run) || ENV["LAUNCHY_DRY_RUN"]
+      Launchy.debug        = leftover.delete(:debug) || ENV.fetch("LAUNCHY_DEBUG", nil)
+      Launchy.application  = leftover.delete(:application) || ENV.fetch("LAUNCHY_APPLICATION", nil)
+      Launchy.host_os      = leftover.delete(:host_os) || ENV.fetch("LAUNCHY_HOST_OS", nil)
+      Launchy.dry_run      = leftover.delete(:dry_run) || ENV.fetch("LAUNCHY_DRY_RUN", nil)
     end
 
     def debug=(enabled)
@@ -104,7 +104,7 @@ def debug=(enabled)
     # we may do logging before a call to 'open', hence the need to check
     # LAUNCHY_DEBUG here
     def debug?
-      @debug || to_bool(ENV["LAUNCHY_DEBUG"])
+      @debug || to_bool(ENV.fetch("LAUNCHY_DEBUG", nil))
     end
 
     def application=(app)
@@ -112,7 +112,7 @@ def application=(app)
     end
 
     def application
-      @application || ENV["LAUNCHY_APPLICATION"]
+      @application || ENV.fetch("LAUNCHY_APPLICATION", nil)
     end
 
     def host_os=(host_os)
@@ -120,7 +120,7 @@ def host_os=(host_os)
     end
 
     def host_os
-      @host_os || ENV["LAUNCHY_HOST_OS"]
+      @host_os || ENV.fetch("LAUNCHY_HOST_OS", nil)
     end
 
     def dry_run=(dry_run)
@@ -128,7 +128,7 @@ def dry_run=(dry_run)
     end
 
     def dry_run?
-      @dry_run || to_bool(ENV["LAUNCHY_DRY_RUN"])
+      @dry_run || to_bool(ENV.fetch("LAUNCHY_DRY_RUN", nil))
     end
 
     def bug_report_message
diff --git a/lib/launchy/detect/nix_desktop_environment.rb b/lib/launchy/detect/nix_desktop_environment.rb
index 380bab6..556dc32 100644
--- a/lib/launchy/detect/nix_desktop_environment.rb
+++ b/lib/launchy/detect/nix_desktop_environment.rb
@@ -36,7 +36,7 @@ def self.browsers
       # KDE desktop environment
       class Kde < NixDesktopEnvironment
         def self.is_current_desktop_environment?
-          ENV["KDE_FULL_SESSION"] &&
+          ENV.fetch("KDE_FULL_SESSION", nil) &&
             Launchy::Application.find_executable("kde-open")
         end
 
@@ -48,7 +48,7 @@ def self.browser
       # Gnome desktop environment
       class Gnome < NixDesktopEnvironment
         def self.is_current_desktop_environment?
-          ENV["GNOME_DESKTOP_SESSION_ID"] &&
+          ENV.fetch("GNOME_DESKTOP_SESSION_ID", nil) &&
             Launchy::Application.find_executable("gnome-open")
         end
 
diff --git a/spec/detect/host_os_family_spec.rb b/spec/detect/host_os_family_spec.rb
index b0c440c..3a156f3 100644
--- a/spec/detect/host_os_family_spec.rb
+++ b/spec/detect/host_os_family_spec.rb
@@ -12,7 +12,7 @@
     Launchy.reset_global_options
   end
 
-  YAML.load_file(File.expand_path("../../tattle-host-os.yaml", __FILE__))["host_os"].keys.sort.each do |os|
+  YAML.load_file(File.expand_path("../tattle-host-os.yaml", __dir__))["host_os"].keys.sort.each do |os|
     it "OS family of #{os} is detected" do
       os_family = Launchy::Detect::HostOsFamily.detect(os)
       _(os_family).must_be_kind_of Launchy::Detect::HostOsFamily