X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pp_hot.c;h=3f85116a31603439adf925248170de4de84966a7;hb=48f7ee7a00a9cc3c53df2208f08bd3848df9a5b5;hp=9b0573bb03235bb652bfdae40a0331f45bc69a8e;hpb=790090df87a94d63cdbf866bce162581c29c2abf;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/pp_hot.c b/pp_hot.c
index 9b0573b..3f85116 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -172,8 +172,12 @@ PP(pp_concat)
 		/* Take a copy since we're about to overwrite TARG */
 		olds = s = (U8*)savepvn((char*)s, len);
 	    }
-	    if (!SvOK(left) && SvTYPE(left) <= SVt_PVMG)
-		sv_setpv(left, "");	/* Suppress warning. */
+	    if (!SvOK(left) && SvTYPE(left) <= SVt_PVMG) {
+	        if (SvREADONLY(left))
+		    left = sv_2mortal(newSVsv(left));
+		else
+		    sv_setpv(left, "");	/* Suppress warning. */
+	    }
             l = (U8*)SvPV(left, targlen);
 	    left_utf |= DO_UTF8(left);
             if (TARG != left)