diff --git a/engines/lualatex.rb b/engines/lualatex.rb
index 4bcbfeb..adfbb2c 100644
--- a/engines/lualatex.rb
+++ b/engines/lualatex.rb
@@ -39,7 +39,7 @@ def hash_result
                           without: /\/CreationDate|\/ModDate|\/ID|\/Type\/XRef\/Index/)
   end
 
-  def exec()
+  def exec
     @old_hash = hash_result
     
     # Command for the main LaTeX compilation work
@@ -49,7 +49,7 @@ def exec()
     f = IO::popen(eval(lualatex))
     log = f.readlines.map! { |s| Log.fix(s) }
 
-    [File.exist?(@target_file), TeXLogParser.parse(log), log.join('').strip!]
+    { success: File.exist?(@target_file), messages: TeXLogParser.parse(log), log: log.join('').strip! }
   end
 end
 
diff --git a/engines/pdflatex.rb b/engines/pdflatex.rb
index 1962a1d..39d3715 100644
--- a/engines/pdflatex.rb
+++ b/engines/pdflatex.rb
@@ -38,7 +38,7 @@ def hash_result
     HashManager.hash_file(@target_file, without: /\/CreationDate|\/ModDate|\/ID/)
   end
 
-  def exec()
+  def exec
     @old_hash = hash_result
 
     # Command for the main LaTeX compilation work
@@ -48,7 +48,7 @@ def exec()
     f = IO::popen(eval(pdflatex))
     log = f.readlines.map! { |s| Log.fix(s) }
 
-    [File.exist?(@target_file), TeXLogParser.parse(log), log.join('').strip!]
+    { success: File.exist?(@target_file), messages: TeXLogParser.parse(log), log: log.join('').strip! }
   end
 end
 
diff --git a/engines/xelatex.rb b/engines/xelatex.rb
index 8c8b9ce..302f104 100644
--- a/engines/xelatex.rb
+++ b/engines/xelatex.rb
@@ -38,7 +38,7 @@ def hash_result
     HashManager.hash_file(@target_file, drop_from: /CIDFontType0C|Type1C/)
   end
 
-  def exec()
+  def exec
     @old_hash = hash_result
     
     # Command for the main LaTeX compilation work
@@ -48,7 +48,7 @@ def exec()
     f = IO::popen(eval(xelatex))
     log = f.readlines.map! { |s| Log.fix(s) }
 
-    [File.exist?(@target_file), TeXLogParser.parse(log), log.join('').strip!]
+    { success: File.exist?(@target_file), messages: TeXLogParser.parse(log), log: log.join('').strip! }
   end
 end
 
diff --git a/lib/Engine.rb b/lib/Engine.rb
index 07129df..0acefd4 100644
--- a/lib/Engine.rb
+++ b/lib/Engine.rb
@@ -56,17 +56,17 @@ def initialize
 
   public
     # Returns true iff this engine needs to run (again)
-    def do?()
+    def do?
       false
     end
 
     # Executes this engine
-    # Returns an array with three elements
-    #  1. true iff there were no fatal errors
-    #  2. A list of log messages (cf LogMessage)
-    #  3. The raw output of the external program
-    def exec()
-      [true, ['No execution code, need to overwrite!'], 'No execution code, need to overwrite!']
+    # Returns a dictionary with three entries:
+    #  - sucess: true iff there were no fatal errors
+    #  - messages: A list of log messages (cf LogMessage)
+    #  - log: The raw output of the external program
+    def exec
+      { success: true, messages: ['No execution code, need to overwrite!'], log: 'No execution code, need to overwrite!' }
     end
 
     def name
diff --git a/ltx2any.rb b/ltx2any.rb
index 4a901cb..6034e79 100644
--- a/ltx2any.rb
+++ b/ltx2any.rb
@@ -181,9 +181,9 @@
         # Run engine
         OUTPUT.start("#{engine.name}(#{run}) running")
         result = engine.exec
-        OUTPUT.stop(if result[0] then :success else :error end)
+        OUTPUT.stop(if result[:success] then :success else :error end)
 
-        break if !File.exist?("#{PARAMS[:jobname]}.#{engine.extension}")
+        break unless File.exist?("#{PARAMS[:jobname]}.#{engine.extension}")
 
         # Run extensions that need to do something after this iteration
         Extension.run_all(run, OUTPUT, log)
@@ -194,7 +194,7 @@
       end
 
       # Save log messages of last engine run
-      log.add_messages(engine.name, :engine, result[1], result[2])
+      log.add_messages(engine.name, :engine, result[:messages], result[:log])
 
       # Run extensions that may need to do something after all engine runs
       Extension.run_all(:after, OUTPUT, log)