diff --git a/src/u256.rs b/src/u256.rs
index b519bb2..3e4d167 100644
--- a/src/u256.rs
+++ b/src/u256.rs
@@ -122,7 +122,7 @@ impl U256 {
     pub fn from_string(string: &str) -> Result<Self, ParseUintError> {
         let mut value = U256::ZERO;
 
-        for chr in string.chars() {
+        for chr in string.chars().filter(|c| *c != '_') {
             let digit = chr.to_digit(10);
             if let Some(dig) = digit {
                 let (value_x_8, value_x_2) = (value << 3, value << 1);
@@ -178,7 +178,7 @@ impl U256 {
             _ => 0,
         };
 
-        for chr in string.chars().skip(skip) {
+        for chr in string.chars().skip(skip).filter(|c| *c != '_') {
             let digit = chr.to_digit(radix);
 
             if let Some(dig) = digit {
diff --git a/src/u512.rs b/src/u512.rs
index 29c9b47..3d12856 100644
--- a/src/u512.rs
+++ b/src/u512.rs
@@ -1855,7 +1855,8 @@ mod test {
         assert_eq!(a % b, "229622695252588468980047866375".parse::<U512>()?);
 
         let a = "3912093812908391208428194902184908123982189742178629873982173391238912".parse::<U512>()?;
-        let b = "940899340494892899287232134329048329473287439824732982141".parse::<U512>()?;
+        let b = "940899340494892899287232134329048329473287439824732982141"
+            .parse::<U512>()?;
         let c = a % b;
 
         assert_eq!(