diff --git a/X2Log.Constants.pas b/X2Log.Constants.pas
index 09b6b94..cf30473 100644
--- a/X2Log.Constants.pas
+++ b/X2Log.Constants.pas
@@ -21,14 +21,32 @@ resourcestring
     X2Log.Observer.LogFile
   }
 
+  { The format of the log line without a category
+
+      0: Message
+  }
+  LogFileLineNoCategory = '%0:s';
+
+  { The format of the log line with a category
+
+      0: Message
+      1: Category
+  }
+  LogFileLineCategory = '%1:s: %0:s';
+
+
   { Date format used to determine the file name of detail files }
   LogFileNameDateFormat = 'yyyymmdd_hhnn';
 
   { Date format used in log files }
   LogFileLineDateFormat = 'yyyy-mm-dd hh:nn';
 
-  { The text added to the message if details are stored externally }
-  LogFileLineDetails = ' (details: %s)';
+  { The format of the log message when details are stored externally
+
+      0: Message
+      1: Details filename
+   }
+  LogFileLineDetails = '%0:s (details: %1:s)';
 
 
   {
diff --git a/X2Log.Observer.LogFile.pas b/X2Log.Observer.LogFile.pas
index fa4634a..58672dc 100644
--- a/X2Log.Observer.LogFile.pas
+++ b/X2Log.Observer.LogFile.pas
@@ -117,7 +117,11 @@ var
 
 begin
   ForceDirectories(ExtractFilePath(FileName));
-  errorMsg := AEntry.Message;
+
+  if Length(AEntry.Category) > 0 then
+    errorMsg := Format(GetLogResourceString(@LogFileLineCategory), [AEntry.Message, AEntry.Category])
+  else
+    errorMsg := Format(GetLogResourceString(@LogFileLineNoCategory), [AEntry.Message]);
 
   if Supports(AEntry.Details, IX2LogDetailsStreamable, logDetailsStreamable) then
   begin
@@ -160,7 +164,7 @@ begin
 
     //      ErrorLogs.Add(reportFileName);
 
-          errorMsg := errorMsg + Format(GetLogResourceString(@LogFileLineDetails), [ExtractFileName(detailsFileName)]);
+          errorMsg := Format(GetLogResourceString(@LogFileLineDetails), [errorMsg, ExtractFileName(detailsFileName)]);
           break;
         end;
       until False;