diff --git a/src/deepl.cr b/src/deepl.cr
index 2c8b11b..de76367 100644
--- a/src/deepl.cr
+++ b/src/deepl.cr
@@ -30,7 +30,11 @@ module DeepL
 
     puts translated_text
   rescue ex
-    STDERR.puts "ERROR: #{ex.class} #{ex.message}"
+    if DeepLError.debug
+      STDERR.puts "[deepl-cli] ERROR: #{ex.class} #{ex.message}\n#{ex.backtrace.join("\n")}"
+    else
+      STDERR.puts "[deepl-cli] ERROR: #{ex.class} #{ex.message}"
+    end
     exit(1)
   end
 end
diff --git a/src/deepl/parser.cr b/src/deepl/parser.cr
index c2c38bb..64a3136 100644
--- a/src/deepl/parser.cr
+++ b/src/deepl/parser.cr
@@ -48,7 +48,7 @@ module DeepL
         show_help
       end
       invalid_option do |flag|
-        STDERR.puts "ERROR: #{flag} is not a valid option."
+        STDERR.puts "[deepl-cli] ERROR: #{flag} is not a valid option."
         STDERR.puts self
         exit(1)
       end