diff --git a/src/uu/numfmt/src/numfmt.rs b/src/uu/numfmt/src/numfmt.rs
index 304727c2a7e..a2152a0c966 100644
--- a/src/uu/numfmt/src/numfmt.rs
+++ b/src/uu/numfmt/src/numfmt.rs
@@ -600,28 +600,32 @@ pub fn uu_app() -> Command {
                 .long(FROM)
                 .help(translate!("numfmt-help-from"))
                 .value_name("UNIT")
-                .default_value(FROM_DEFAULT),
+                .default_value(FROM_DEFAULT)
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(FROM_UNIT)
                 .long(FROM_UNIT)
                 .help(translate!("numfmt-help-from-unit"))
                 .value_name("N")
-                .default_value(FROM_UNIT_DEFAULT),
+                .default_value(FROM_UNIT_DEFAULT)
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(TO)
                 .long(TO)
                 .help(translate!("numfmt-help-to"))
                 .value_name("UNIT")
-                .default_value(TO_DEFAULT),
+                .default_value(TO_DEFAULT)
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(TO_UNIT)
                 .long(TO_UNIT)
                 .help(translate!("numfmt-help-to-unit"))
                 .value_name("N")
-                .default_value(TO_UNIT_DEFAULT),
+                .default_value(TO_UNIT_DEFAULT)
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(PADDING)
@@ -652,7 +656,8 @@ pub fn uu_app() -> Command {
                     "from-zero",
                     "towards-zero",
                     "nearest",
-                ])),
+                ]))
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(SUFFIX)
@@ -665,7 +670,8 @@ pub fn uu_app() -> Command {
             Arg::new(UNIT_SEPARATOR)
                 .long(UNIT_SEPARATOR)
                 .help(translate!("numfmt-help-unit-separator"))
-                .value_name("STRING"),
+                .value_name("STRING")
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(INVALID)
@@ -673,7 +679,8 @@ pub fn uu_app() -> Command {
                 .help(translate!("numfmt-help-invalid"))
                 .default_value("abort")
                 .value_parser(["abort", "fail", "warn", "ignore"])
-                .value_name("INVALID"),
+                .value_name("INVALID")
+                .allow_hyphen_values(true),
         )
         .arg(
             Arg::new(ZERO_TERMINATED)
diff --git a/tests/by-util/test_numfmt.rs b/tests/by-util/test_numfmt.rs
index a17e634bd25..5d3382bd6e4 100644
--- a/tests/by-util/test_numfmt.rs
+++ b/tests/by-util/test_numfmt.rs
@@ -173,11 +173,44 @@ fn test_delimiter_hyphen_leading_as_separate_arg() {
     // unrecognized flag.
     new_ucmd!()
         .args(&["-d", "-x", "--field=1"])
-        .pipe_in("5-x6")
         .fails()
         .stderr_contains("the delimiter must be a single character");
 }
 
+#[test]
+fn test_unit_size_hyphen_leading_as_separate_arg() {
+    // A hyphen-leading unit size passed as its own argument must reach
+    // our own validation instead of being read as an unknown flag.
+    for opt in ["--from-unit", "--to-unit"] {
+        new_ucmd!()
+            .args(&[opt, "-1"])
+            .pipe_in("5\n")
+            .fails()
+            .stderr_contains("invalid unit size: '-1'");
+    }
+}
+
+#[test]
+fn test_unit_hyphen_leading_as_separate_arg() {
+    // Same for the --from/--to units.
+    for opt in ["--from", "--to"] {
+        new_ucmd!()
+            .args(&[opt, "-x"])
+            .pipe_in("5\n")
+            .fails()
+            .stderr_contains("invalid argument '-x' for '--");
+    }
+}
+
+#[test]
+fn test_unit_separator_hyphen_leading_as_separate_arg() {
+    new_ucmd!()
+        .args(&["--to=si", "--unit-separator", "-"])
+        .pipe_in("1000\n")
+        .succeeds()
+        .stdout_is("1.0-k\n");
+}
+
 #[test]
 fn test_header() {
     new_ucmd!()