diff --git a/ujit_iface.c b/ujit_iface.c
index 91d3621b43..591d9c044c 100644
--- a/ujit_iface.c
+++ b/ujit_iface.c
@@ -397,7 +397,7 @@ ujit_disasm(VALUE self, VALUE code, VALUE from)
     cs_insn *insns;
 
     TypedData_Get_Struct(self, csh, &ujit_disasm_type, handle);
-    count = cs_disasm(*handle, StringValuePtr(code), RSTRING_LEN(code), NUM2INT(from), 0, &insns);
+    count = cs_disasm(*handle, (uint8_t *)StringValuePtr(code), RSTRING_LEN(code), NUM2INT(from), 0, &insns);
     VALUE insn_list = rb_ary_new_capa(count);
 
     for (size_t i = 0; i < count; i++) {