diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index 7547d0431e..c6532f7aa6 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -30,7 +30,6 @@ extern size_t onig_region_memsize(const struct re_registers *regs);
 
 static VALUE StringScanner;
 static VALUE ScanError;
-static ID id_byteslice;
 
 static int usascii_encindex, utf8_encindex, binary_encindex;
 
@@ -2287,8 +2286,6 @@ Init_strscan(void)
     ID id_scanerr = rb_intern("ScanError");
     VALUE tmp;
 
-    id_byteslice = rb_intern("byteslice");
-
     usascii_encindex = rb_usascii_encindex();
     utf8_encindex = rb_utf8_encindex();
     binary_encindex = rb_ascii8bit_encindex();