diff --git a/applications/utilities/preProcessing/mapFieldsPar/createTimes.H b/applications/utilities/preProcessing/mapFieldsPar/createTimes.H
index 10c7117cf6..9d465715b8 100644
--- a/applications/utilities/preProcessing/mapFieldsPar/createTimes.H
+++ b/applications/utilities/preProcessing/mapFieldsPar/createTimes.H
@@ -1,21 +1,15 @@
     Info<< "\nCreate databases as time" << endl;
 
-    const string caseDirOrig = getEnv("FOAM_CASE");
-    const string caseNameOrig = getEnv("FOAM_CASENAME");
-    setEnv("FOAM_CASE", rootDirSource/caseDirSource, true);
-    setEnv("FOAM_CASENAME", caseDirSource, true);
-    Time runTimeSource
-    (
-        Time::controlDictName,
-        rootDirSource,
-        caseDirSource
-    );
-    setEnv("FOAM_CASE", caseDirOrig, true);
-    setEnv("FOAM_CASENAME", caseNameOrig, true);
+    HashTable<string> srcOptions(args.options());
+    srcOptions.erase("case");
+    srcOptions.insert("case", fileName(rootDirSource/caseDirSource));
 
-    Time runTimeTarget
-    (
-        Time::controlDictName,
-        rootDirTarget,
-        caseDirTarget
-    );
+    argList argsSrc(args, srcOptions, false, false, false);
+    if (!argsSrc.checkRootCase())
+    {
+        FatalError.exit();
+    }
+
+    Time runTimeSource(Time::controlDictName, argsSrc);
+
+    Time runTimeTarget(Time::controlDictName, args);
diff --git a/applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C b/applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C
index c6b0929b82..d0e73d77eb 100644
--- a/applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C
+++ b/applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2021 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -204,7 +204,7 @@ int main(int argc, char *argv[])
         "skip mapping lagrangian positions and fields"
     );
 
-    argList args(argc, argv);
+    #include "setRootCase.H"
 
     fileName rootDirTarget(args.rootPath());
     fileName caseDirTarget(args.globalCaseName());