1 files changed, 3 insertions, 0 deletions
diff --git a/pp_sys.c b/pp_sys.c
index c7212b3f32..71c5ca741d 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -1017,7 +1017,10 @@ PP(pp_dbmopen)
     if (SvIV(right))
 	mPUSHu(O_RDWR|O_CREAT);
     else
+    {
 	mPUSHu(O_RDWR);
+	if (!SvOK(right)) right = &PL_sv_no;
+    }
     PUSHs(right);
     PUTBACK;
     call_sv(MUTABLE_SV(GvCV(gv)), G_SCALAR);