diff --git a/lingucomponent/source/thesaurus/libnth/nthesimp.cxx b/lingucomponent/source/thesaurus/libnth/nthesimp.cxx
index 3438d2dbe055..a373e30226a6 100644
--- a/lingucomponent/source/thesaurus/libnth/nthesimp.cxx
+++ b/lingucomponent/source/thesaurus/libnth/nthesimp.cxx
@@ -76,6 +76,7 @@ Thesaurus::Thesaurus() :
     aTLocs = NULL;
     aTNames = NULL;
     numthes = 0;
+    prevLocale = LANGUAGE_DONTKNOW;
 }