diff --git a/src/regexp_bt.c b/src/regexp_bt.c
index 476f34e..2960bad 100644
--- a/src/regexp_bt.c
+++ b/src/regexp_bt.c
@@ -4805,21 +4805,24 @@
     if (backpos.ga_maxlen > BACKPOS_INITIAL)
 	ga_clear(&backpos);
 
-    // Make sure the end is never before the start.  Can happen when \zs and
-    // \ze are used.
-    if (REG_MULTI)
+    if (retval > 0)
     {
-	lpos_T *start = &rex.reg_mmatch->startpos[0];
-	lpos_T *end = &rex.reg_mmatch->endpos[0];
+	// Make sure the end is never before the start.  Can happen when \zs
+	// and \ze are used.
+	if (REG_MULTI)
+	{
+	    lpos_T *start = &rex.reg_mmatch->startpos[0];
+	    lpos_T *end = &rex.reg_mmatch->endpos[0];
 
-	if (end->lnum < start->lnum
+	    if (end->lnum < start->lnum
 			|| (end->lnum == start->lnum && end->col < start->col))
-	    rex.reg_mmatch->endpos[0] = rex.reg_mmatch->startpos[0];
-    }
-    else
-    {
-	if (rex.reg_match->endp[0] < rex.reg_match->startp[0])
-	    rex.reg_match->endp[0] = rex.reg_match->startp[0];
+		rex.reg_mmatch->endpos[0] = rex.reg_mmatch->startpos[0];
+	}
+	else
+	{
+	    if (rex.reg_match->endp[0] < rex.reg_match->startp[0])
+		rex.reg_match->endp[0] = rex.reg_match->startp[0];
+	}
     }
 
     return retval;