diff --git a/src/perl/make_parameter_source.pl b/src/perl/make_parameter_source.pl
--- a/src/perl/make_parameter_source.pl
+++ b/src/perl/make_parameter_source.pl
@@ -88,8 +88,8 @@ while (<parfile>) {
 $lines=$i;
 
 print cppfile <<END_HEADER;
-// WARNING: This file is automatically generated by make_parameter_source.pl. Do not edit.
-    // All edits will be discarded.
+// WARNING: This file is automatically generated by make_parameter_source.pl.
+// Do not edit. All edits will be discarded.
 
 #include "parameter.h"
 #include <cstdio>
@@ -115,6 +115,9 @@ for ($i=0;$i<$lines;$i++) {
     if ($convtype[$i] ne "label" && $convtype[$i] ne "title") {
 	if ($convtype[$i] eq "char *") {
 	    print cppfile "  $param[$i] = strdup($value[$i]);\n";
+	    if ($param[$i] eq "datadir") {
+		print cppfile "  datadir = AppendHomeDirIfPathRelative(datadir);\n";
+	    }
 	} else {
 	    if ($convtype[$i] eq "double *") {
                 #comma separated list expected
@@ -133,13 +136,6 @@ for ($i=0;$i<$lines;$i++) {
 
 
 print cppfile <<END_HEADER3;
-  // reassign datadir outside the loop
-  QDir dataDir(datadir);
-  if (dataDir.isRelative()){
-    QStringList path;
-    path << QDir::homePath() << dataDir.dirName();
-    datadir = strdup((char *) path.join("/").toStdString().c_str());
-  }
 }
 
 Parameter::~Parameter() {
@@ -190,6 +186,9 @@ for ($i=0;$i<$lines;$i++) {
 	print cppfile "  $param[$i] = $funname{$convtype[$i]}(fp, \"$param[$i]\", $length, true);\n";
     } else {
 	print cppfile "  $param[$i] = $funname{$convtype[$i]}(fp, \"$param[$i]\", $value[$i], true);\n";
+	if ($param[$i] eq "datadir") {
+	    print cppfile "  datadir = AppendHomeDirIfPathRelative(datadir);\n";
+	}
     }
     if ($type[$i] eq "directory") {
 	print cppfile "  if (strcmp($param[$i], \".\"))\n";
@@ -230,11 +229,21 @@ for ($i=0;$i<$lines;$i++) {
 	if ($convtype[$i] eq "bool") {
 	    print cppfile "  os << \" $param[$i] = \" << sbool($param[$i]) << endl;\n";
 	} else {
-	    if ($convtype[$i] eq "char *") {
-		print cppfile "\n  if ($param[$i]) \n";
-		print cppfile "  ";
+
+	    if (($convtype[$i] eq "char *") and ($param[$i] eq "datadir")) {
+                print cppfile "  if (datadir) {
+                                     QDir dataDir = QDir::home().relativeFilePath(datadir);
+                                     os << \" datadir = \" << dataDir.dirName().toStdString() << endl;
+                                 }
+                                 else {
+                                     os << \"datadir = .\" << endl;
+                                 }\n";
+	    } else {
+		if ($convtype[$i] eq "char *") {
+		    print cppfile "\n  if ($param[$i]) \n";
+		}
+		print cppfile "  os << \" $param[$i] = \" << $param[$i] << endl;\n";
 	    }
-	    print cppfile "  os << \" $param[$i] = \" << $param[$i] << endl;\n";
 	}
     }
 }
@@ -272,11 +281,17 @@ for ($i=0;$i<$lines;$i++) {
 	if ($convtype[$i] eq "bool") {
 	    print cppfile "text << sbool($param[$i]);\n";
 	} else {
-	    if ($convtype[$i] eq "char *") {
-		print cppfile "\n  if ($param[$i]) \n";
-		print cppfile "  ";
+	    if (($convtype[$i] eq "char *") and ($param[$i] eq "datadir")) {
+                print cppfile "\n  if ($param[$i]) {
+                                     QDir dataDir = QDir::home().relativeFilePath(datadir);
+                                     text << dataDir.dirName().toStdString();
+                                   }\n";
+	    } else {
+		if ($convtype[$i] eq "char *") {
+		    print cppfile "\n  if ($param[$i]) \n";
+		}
+		print cppfile "    text << $param[$i];\n";
 	    }
-	    print cppfile "  text << $param[$i];\n";
 	}
     }
     print cppfile "xmlNewProp(xmlpar, BAD_CAST \"val\", BAD_CAST text.str().c_str());\n";
@@ -304,6 +319,9 @@ for ($i=0;$i<$lines;$i++) {
 	    if ($convtype[$i] eq "char *") {
 		print cppfile "  if ($param[$i]) { free($param[$i]); }\n";
 		print cppfile "  $param[$i]=strdup(valc);\n";
+		if ($param[$i] eq "datadir") {
+		    print cppfile "  datadir = AppendHomeDirIfPathRelative(datadir);\n";
+		}
 	    } else {
 		if ($convtype[$i] eq "int") {
 		    print cppfile "  $param[$i] = standardlocale.toInt(valc, &ok);\n";
@@ -338,19 +356,6 @@ for ($i=0;$i<$lines;$i++) {
     }
 }
 
-print cppfile <<END_DATADIR;
-// reassign datadir outside the loop
-if (!strcmp(namec, "datadir")) {
-  if (datadir) { free(datadir); }
-  QDir dataDir(datadir);
-  if (dataDir.isRelative()){
-    QStringList path;
-    path << QDir::homePath() << dataDir.dirName();
-    datadir = strdup((char *) path.join("/").toStdString().c_str());
-  }
- }
-END_DATADIR
-
 print cppfile "}\n";
 
 print cppfile <<END_TRAILER;