diff --git a/src/uu/seq/src/seq.rs b/src/uu/seq/src/seq.rs
index aac8f2280..a76a23c4e 100644
--- a/src/uu/seq/src/seq.rs
+++ b/src/uu/seq/src/seq.rs
@@ -88,30 +88,65 @@ impl FromStr for Number {
         if s.starts_with('+') {
             s = &s[1..];
         }
+        let is_neg = s.starts_with('-');
 
-        match s.parse::<BigInt>() {
-            Ok(n) => {
-                // If `s` is '-0', then `parse()` returns
-                // `BigInt::zero()`, but we need to return
-                // `Number::MinusZero` instead.
-                if n == BigInt::zero() && s.starts_with('-') {
-                    Ok(Number::MinusZero)
-                } else {
-                    Ok(Number::BigInt(n))
+        match s.to_lowercase().find("0x") {
+            Some(i) if i <= 1 => match &s.as_bytes()[i + 2] {
+                    b'-' | b'+' => Err(format!(
+                    "invalid hexadecimal argument: {}\nTry '{} --help' for more information.",
+                    s.quote(),
+                    uucore::execution_phrase(),
+                )),
+                    // TODO: hexadecimal floating point parsing (see #2660)
+                    b'.' => Err(format!(
+                    "NotImplemented: hexadecimal floating point numbers: {}\nTry '{} --help' for more information.",
+                    s.quote(),
+                    uucore::execution_phrase(),
+                )),
+                    _ => {
+                        let num = BigInt::from_str_radix(&s[i + 2..], 16)
+                            .map_err(|_| format!(
+                    "invalid hexadecimal argument: {}\nTry '{} --help' for more information.",
+                    s.quote(),
+                    uucore::execution_phrase(),
+                ))?;
+                        match (is_neg, num == BigInt::zero()) {
+                            (true, true) => Ok(Number::MinusZero),
+                            (true, false) => Ok(Number::BigInt(-num)),
+                            (false, _) => Ok(Number::BigInt(num)),
+                        }
+                    }
+                },
+            Some(_) => Err(format!(
+                "invalid hexadecimal argument: {}\nTry '{} --help' for more information.",
+                s.quote(),
+                uucore::execution_phrase(),
+            )),
+
+            None => match s.parse::<BigInt>() {
+                Ok(n) => {
+                    // If `s` is '-0', then `parse()` returns
+                    // `BigInt::zero()`, but we need to return
+                    // `Number::MinusZero` instead.
+                    if n == BigInt::zero() && is_neg {
+                        Ok(Number::MinusZero)
+                    } else {
+                        Ok(Number::BigInt(n))
+                    }
                 }
-            }
-            Err(_) => match s.parse::<f64>() {
-                Ok(value) if value.is_nan() => Err(format!(
+                Err(_) => match s.parse::<f64>() {
+                    Ok(value) if value.is_nan() => Err(format!(
                     "invalid 'not-a-number' argument: {}\nTry '{} --help' for more information.",
                     s.quote(),
                     uucore::execution_phrase(),
                 )),
-                Ok(value) => Ok(Number::F64(value)),
-                Err(_) => Err(format!(
+                    Ok(value) => Ok(Number::F64(value)),
+                    Err(_) => Err(format!(
                     "invalid floating point argument: {}\nTry '{} --help' for more information.",
                     s.quote(),
                     uucore::execution_phrase(),
                 )),
+                },
             },
         }
     }
diff --git a/tests/by-util/test_seq.rs b/tests/by-util/test_seq.rs
index 27b5f99bc..6ed3cb67d 100644
--- a/tests/by-util/test_seq.rs
+++ b/tests/by-util/test_seq.rs
@@ -1,6 +1,69 @@
 use crate::common::util::*;
 use std::io::Read;
 
+#[test]
+fn test_hex_rejects_sign_after_identifier() {
+    new_ucmd!()
+        .args(&["0x-123ABC"])
+        .fails()
+        .no_stdout()
+        .stderr_contains("invalid hexadecimal argument: '0x-123ABC'")
+        .stderr_contains("for more information.");
+    new_ucmd!()
+        .args(&["0x+123ABC"])
+        .fails()
+        .no_stdout()
+        .stderr_contains("invalid hexadecimal argument: '0x+123ABC'")
+        .stderr_contains("for more information.");
+    new_ucmd!()
+        .args(&["-0x-123ABC"])
+        .fails()
+        .no_stdout()
+        .stderr_contains("invalid hexadecimal argument: '-0x-123ABC'")
+        .stderr_contains("for more information.");
+    new_ucmd!()
+        .args(&["-0x+123ABC"])
+        .fails()
+        .no_stdout()
+        .stderr_contains("invalid hexadecimal argument: '-0x+123ABC'")
+        .stderr_contains("for more information.");
+}
+
+#[test]
+fn test_hex_lowercase_uppercase() {
+    new_ucmd!()
+        .args(&["0xa", "0xA"])
+        .succeeds()
+        .stdout_is("10\n");
+    new_ucmd!()
+        .args(&["0Xa", "0XA"])
+        .succeeds()
+        .stdout_is("10\n");
+}
+
+#[test]
+fn test_hex_big_number() {
+    new_ucmd!()
+        .args(&[
+            "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
+            "0x100000000000000000000000000000000",
+        ])
+        .succeeds()
+        .stdout_is(
+            "340282366920938463463374607431768211455\n340282366920938463463374607431768211456\n",
+        );
+}
+
+#[test]
+fn test_hex_identifier_in_wrong_place() {
+    new_ucmd!()
+        .args(&["1234ABCD0x"])
+        .fails()
+        .no_stdout()
+        .stderr_contains("invalid hexadecimal argument: '1234ABCD0x'")
+        .stderr_contains("for more information.");
+}
+
 #[test]
 fn test_rejects_nan() {
     let ts = TestScenario::new(util_name!());