diff --git a/asm/directiv.c b/asm/directiv.c
index b8e41dcf..1d6f5c80 100644
--- a/asm/directiv.c
+++ b/asm/directiv.c
@@ -396,7 +396,7 @@ bool process_directives(char *directive)
             value++;        /* skip escaping $ if present */
             validid = nasm_isidchar(*value);
             if (globl.dollarhex)
-                validid &= !nasm_isnumstart(value[1]);
+                validid &= !nasm_isnumstart(value[0]);
         } else {
             validid = nasm_isidstart(*value);
         }