diff --git a/src/functionObjects/utilities/caseInfo/caseInfo.C b/src/functionObjects/utilities/caseInfo/caseInfo.C
index caec64d935..3d65aba454 100644
--- a/src/functionObjects/utilities/caseInfo/caseInfo.C
+++ b/src/functionObjects/utilities/caseInfo/caseInfo.C
@@ -420,12 +420,13 @@ bool Foam::functionObjects::caseInfo::read(const dictionary& dict)
     if (stateFunctionObject::read(dict) && writeFile::read(dict))
     {
         writeFormatNames_.readIfPresent("writeFormat", dict, writeFormat_);
+        writeFile::setExt("." + writeFormatNames_[writeFormat_]);
+
         lookupModeNames_.readIfPresent("lookupMode", dict, lookupMode_);
 
         dictionaries_ = dict.subOrEmptyDict("dictionaries");
 
-        functionObjectNames_ =
-            dict.getOrDefault<wordList>("functionObjects", wordList());
+        dict.readIfPresent("functionObjects", functionObjectNames_);
 
         return true;
     }