diff --git a/tecsdriv.c b/tecsdriv.c
index 87c71fff..38206f28 100644
--- a/tecsdriv.c
+++ b/tecsdriv.c
@@ -206,7 +206,11 @@
      assert(pMe);
 
      *iCode = pMe->iLastError;
-     str_ncpy(error, pMe->lastError, iErrLen);
+     if (pMe->lastError==NULL) {
+       str_ncpy(error, "undefined error", iErrLen);
+     } else {
+       str_ncpy(error, pMe->lastError, iErrLen);
+     }
      return 1;
   }
 /*---------------------------------------------------------------------------*/