diff --git a/Python/peephole.c b/Python/peephole.c
index ab96ce9..4bc65dc 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -535,7 +535,8 @@
                 }
                 if (codestr[i+3] != UNPACK_SEQUENCE  ||
                     !ISBASICBLOCK(blocks,i,6) ||
-                    j != GETARG(codestr, i+3))
+                    j != GETARG(codestr, i+3) ||
+                    opcode == BUILD_SET)
                     continue;
                 if (j == 1) {
                     memset(codestr+i, NOP, 6);