diff --git a/src/literals.rs b/src/literals.rs
index becbf8d..32fb6f0 100644
--- a/src/literals.rs
+++ b/src/literals.rs
@@ -1,3 +1,5 @@
+use std::ops::RangeFrom;
+
 use nom::{
     bytes::complete::tag,
     character::complete::{char, one_of},
@@ -8,13 +10,6 @@ use nom::{
 
 use crate::parser::IResult;
 
-pub fn decimal(input: &str) -> IResult<&str, u64> {
-    map_res(
-        recognize(many1(terminated(one_of("0123456789"), many0(char('_'))))),
-        |out: &str| out.parse::<u64>(),
-    )(input)
-}
-
 pub fn hexadecimal(input: &str) -> IResult<&str, u64> {
     map_res(
         preceded(
diff --git a/src/parser.rs b/src/parser.rs
index c8f86d2..bfb69f2 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,7 +1,7 @@
 use nom::{
     branch::alt,
     bytes::complete::tag,
-    character::complete::{alpha1, alphanumeric1, char, multispace0, multispace1},
+    character::complete::{alpha1, alphanumeric1, char, multispace0, multispace1, u64 as decimal},
     combinator::{map, opt, recognize},
     error::{context, ParseError, VerboseError},
     multi::{many0, many1, separated_list0},
@@ -16,7 +16,7 @@ type Span<'a> = LocatedSpan<&'a str>;
 // custom IResult type for VerboseError
 pub type IResult<I, O, E = VerboseError<I>> = nom::IResult<I, O, E>;
 
-use crate::literals::{decimal, hexadecimal};
+use crate::literals::{hexadecimal};
 
 fn ws0<'a, F: 'a, O, E: ParseError<&'a str>>(
     inner: F,