diff --git a/mrbgems/mruby-compiler/core/codegen.c b/mrbgems/mruby-compiler/core/codegen.c
index d198a711c..357440d20 100644
--- a/mrbgems/mruby-compiler/core/codegen.c
+++ b/mrbgems/mruby-compiler/core/codegen.c
@@ -838,7 +838,7 @@ merge_op_string(codegen_scope *s, uint16_t dst, uint16_t b1, uint16_t b2, const
     struct mrb_insn_data data = mrb_decode_insn(i);
     if (data.insn == OP_STRING) {
       if (data.b == b1) used |= 1;
-      else if (data.b == b2) used |= 2;
+      if (data.b == b2) used |= 2;
     }
     switch (i[0]) {
     case OP_EXT1: