diff --git a/packages/fcl-base/src/fpmimetypes.pp b/packages/fcl-base/src/fpmimetypes.pp
index add16b0682..0e20bb6aff 100644
--- a/packages/fcl-base/src/fpmimetypes.pp
+++ b/packages/fcl-base/src/fpmimetypes.pp
@@ -266,7 +266,9 @@ Var
 begin
   T:=FindMimeByType(AMimeType);
   if Assigned(T) then
-    Result:=T.Extensions;
+    Result:=T.Extensions
+  else
+    Result:='';
 end;
 
 function TFPMimeTypes.GetMimeType(const AExtension: String): String;
@@ -276,7 +278,9 @@ Var
 begin
   T:=FindMimeByExt(AExtension);
   if Assigned(T) then
-    Result:=T.MimeType;
+    Result:=T.MimeType
+  else
+    Result:='';
 end;
 
 function TFPMimeTypes.GetKnownMimeTypes(AList: TStrings): Integer;