diff --git a/src/uu/head/src/head.rs b/src/uu/head/src/head.rs
index 3602b4a73..78d769020 100644
--- a/src/uu/head/src/head.rs
+++ b/src/uu/head/src/head.rs
@@ -107,12 +107,7 @@ where
 {
     match parse::parse_num(src) {
         Ok((n, last)) => Ok((closure(n), last)),
-        Err(reason) => match reason {
-            parse::ParseError::Syntax => Err(format!("'{}'", src)),
-            parse::ParseError::Overflow => {
-                Err(format!("'{}': Value too large for defined datatype", src))
-            }
-        },
+        Err(e) => Err(e.to_string()),
     }
 }
 
@@ -473,7 +468,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let args = match HeadOptions::get_from(args) {
         Ok(o) => o,
         Err(s) => {
-            crash!(EXIT_FAILURE, "head: {}", s);
+            crash!(EXIT_FAILURE, "{}", s);
         }
     };
     match uu_head(&args) {
diff --git a/src/uu/head/src/parse.rs b/src/uu/head/src/parse.rs
index 0cf20be42..3b788f819 100644
--- a/src/uu/head/src/parse.rs
+++ b/src/uu/head/src/parse.rs
@@ -1,5 +1,5 @@
-use std::convert::TryFrom;
 use std::ffi::OsString;
+use uucore::parse_size::{parse_size, ParseSizeError};
 
 #[derive(PartialEq, Debug)]
 pub enum ParseError {
@@ -92,92 +92,25 @@ pub fn parse_obsolete(src: &str) -> Option<Result<impl Iterator<Item = OsString>
 }
 /// Parses an -c or -n argument,
 /// the bool specifies whether to read from the end
-pub fn parse_num(src: &str) -> Result<(usize, bool), ParseError> {
-    let mut num_start = 0;
-    let mut chars = src.char_indices();
-    let (mut chars, all_but_last) = match chars.next() {
-        Some((_, c)) => {
-            if c == '-' {
-                num_start += 1;
-                (chars, true)
-            } else {
-                (src.char_indices(), false)
-            }
-        }
-        None => return Err(ParseError::Syntax),
-    };
-    let mut num_end = 0usize;
-    let mut last_char = 0 as char;
-    let mut num_count = 0usize;
-    for (n, c) in &mut chars {
-        if c.is_numeric() {
-            num_end = n;
-            num_count += 1;
-        } else {
-            last_char = c;
-            break;
+pub fn parse_num(src: &str) -> Result<(usize, bool), ParseSizeError> {
+    let mut size_string = src.trim();
+    let mut all_but_last = false;
+
+    if let Some(c) = size_string.chars().next() {
+        if c == '-' {
+            size_string = &size_string[1..];
+            all_but_last = true;
         }
+    } else {
+        return Err(ParseSizeError::ParseFailure(src.to_string()));
     }
 
-    let num = if num_count > 0 {
-        match src[num_start..=num_end].parse::<usize>() {
-            Ok(n) => Some(n),
-            Err(_) => return Err(ParseError::Overflow),
-        }
-    } else {
-        None
-    };
-
-    if last_char == 0 as char {
-        if let Some(n) = num {
-            Ok((n, all_but_last))
-        } else {
-            Err(ParseError::Syntax)
-        }
-    } else {
-        let base: u128 = match chars.next() {
-            Some((_, c)) => {
-                let b = match c {
-                    'B' if last_char != 'b' => 1000,
-                    'i' if last_char != 'b' => {
-                        if let Some((_, 'B')) = chars.next() {
-                            1024
-                        } else {
-                            return Err(ParseError::Syntax);
-                        }
-                    }
-                    _ => return Err(ParseError::Syntax),
-                };
-                if chars.next().is_some() {
-                    return Err(ParseError::Syntax);
-                } else {
-                    b
-                }
-            }
-            None => 1024,
-        };
-        let mul = match last_char.to_lowercase().next().unwrap() {
-            'b' => 512,
-            'k' => base.pow(1),
-            'm' => base.pow(2),
-            'g' => base.pow(3),
-            't' => base.pow(4),
-            'p' => base.pow(5),
-            'e' => base.pow(6),
-            'z' => base.pow(7),
-            'y' => base.pow(8),
-            _ => return Err(ParseError::Syntax),
-        };
-        let mul = match usize::try_from(mul) {
-            Ok(n) => n,
-            Err(_) => return Err(ParseError::Overflow),
-        };
-        match num.unwrap_or(1).checked_mul(mul) {
-            Some(n) => Ok((n, all_but_last)),
-            None => Err(ParseError::Overflow),
-        }
+    match parse_size(&size_string) {
+        Ok(n) => Ok((n, all_but_last)),
+        Err(e) => Err(e),
     }
 }
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -195,44 +128,6 @@ mod tests {
         Some(Ok(src.iter().map(|s| s.to_string()).collect()))
     }
     #[test]
-    #[cfg(not(target_pointer_width = "128"))]
-    fn test_parse_overflow_x64() {
-        assert_eq!(parse_num("1Y"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("1Z"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("100E"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("100000P"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("1000000000T"), Err(ParseError::Overflow));
-        assert_eq!(
-            parse_num("10000000000000000000000"),
-            Err(ParseError::Overflow)
-        );
-    }
-    #[test]
-    #[cfg(target_pointer_width = "32")]
-    fn test_parse_overflow_x32() {
-        assert_eq!(parse_num("1T"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("1000G"), Err(ParseError::Overflow));
-    }
-    #[test]
-    fn test_parse_bad_syntax() {
-        assert_eq!(parse_num("5MiB nonsense"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("Nonsense string"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("5mib"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("biB"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("-"), Err(ParseError::Syntax));
-        assert_eq!(parse_num(""), Err(ParseError::Syntax));
-    }
-    #[test]
-    fn test_parse_numbers() {
-        assert_eq!(parse_num("k"), Ok((1024, false)));
-        assert_eq!(parse_num("MiB"), Ok((1024 * 1024, false)));
-        assert_eq!(parse_num("-5"), Ok((5, true)));
-        assert_eq!(parse_num("b"), Ok((512, false)));
-        assert_eq!(parse_num("-2GiB"), Ok((2 * 1024 * 1024 * 1024, true)));
-        assert_eq!(parse_num("5M"), Ok((5 * 1024 * 1024, false)));
-        assert_eq!(parse_num("5MB"), Ok((5 * 1000 * 1000, false)));
-    }
-    #[test]
     fn test_parse_numbers_obsolete() {
         assert_eq!(obsolete("-5"), obsolete_result(&["-n", "5"]));
         assert_eq!(obsolete("-100"), obsolete_result(&["-n", "100"]));
diff --git a/tests/by-util/test_head.rs b/tests/by-util/test_head.rs
index cf7c9c2ee..349fc05d3 100755
--- a/tests/by-util/test_head.rs
+++ b/tests/by-util/test_head.rs
@@ -242,3 +242,28 @@ hello
 ",
         );
 }
+#[test]
+fn test_head_invalid_num() {
+    new_ucmd!()
+        .args(&["-c", "1024R", "emptyfile.txt"])
+        .fails()
+        .stderr_is("head: invalid number of bytes: ‘1024R’");
+    new_ucmd!()
+        .args(&["-n", "1024R", "emptyfile.txt"])
+        .fails()
+        .stderr_is("head: invalid number of lines: ‘1024R’");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-c", "1Y", "emptyfile.txt"])
+        .fails()
+        .stderr_is(
+            "head: invalid number of bytes: ‘1Y’: Value too large to be stored in data type",
+        );
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-n", "1Y", "emptyfile.txt"])
+        .fails()
+        .stderr_is(
+            "head: invalid number of lines: ‘1Y’: Value too large to be stored in data type",
+        );
+}