diff --git a/include/isam.cpp b/include/isam.cpp
index 5393abb42..1a7f1d860 100755
--- a/include/isam.cpp
+++ b/include/isam.cpp
@@ -1896,10 +1896,16 @@ int TSystemisamfile::update(
         tmpfname.ext("dbf");
         fcopy((const char*)tmpfname,(const char*)fname);
         ::remove((const char*)tmpfname);
-        tmpfname.ext("fpt");
+        if (c & 1)
+          tmpfname.ext("fpt");
+        else
+          tmpfname.ext("dbt");
         if (fexist((const char *) tmpfname))
         {
-          fname.ext("fpt");
+          if (c & 1)
+            fname.ext("fpt");
+          else
+            fname.ext("dbt");
           fcopy((const char*)tmpfname,(const char*)fname);
           ::remove((const char*)tmpfname);
         }