diff --git a/crates/crates-io/lib.rs b/crates/crates-io/lib.rs
index 67e0af4435d..e0197568a6c 100644
--- a/crates/crates-io/lib.rs
+++ b/crates/crates-io/lib.rs
@@ -522,10 +522,11 @@ pub fn check_token(token: &str) -> Result<()> {
         bail!("please provide a non-empty token");
     }
     if token.bytes().all(|b| {
-        b >= 32 // undefined in ISO-8859-1, in ASCII/ UTF-8 not-printable character
-        && b < 128 // utf-8: the first bit signals a multi-byte character
-        && b != 127 // 127 is a control character in ascii and not in ISO 8859-1
-        || b == b't' // tab is also allowed (even when < 32)
+        // This is essentially the US-ASCII limitation of
+        // https://www.rfc-editor.org/rfc/rfc9110#name-field-values. That is,
+        // visible ASCII characters (0x21-0x7e), space, and tab. We want to be
+        // able to pass this in an HTTP header without encoding.
+        b >= 32 && b < 127 || b == b'\t'
     }) {
         Ok(())
     } else {
diff --git a/tests/testsuite/login.rs b/tests/testsuite/login.rs
index 19387aed57c..7ff16fad010 100644
--- a/tests/testsuite/login.rs
+++ b/tests/testsuite/login.rs
@@ -134,40 +134,45 @@ fn invalid_login_token() {
         .build();
     setup_new_credentials();
 
-    let check = |stdin: &str, stderr: &str| {
+    let check = |stdin: &str, stderr: &str, status: i32| {
         cargo_process("login")
             .replace_crates_io(registry.index_url())
             .with_stdout("please paste the token found on [..]/me below")
             .with_stdin(stdin)
             .with_stderr(stderr)
-            .with_status(101)
+            .with_status(status)
             .run();
     };
 
-    check(
-        "😄",
-        "\
-[UPDATING] crates.io index
-[ERROR] token contains invalid characters.
+    let invalid = |stdin: &str| {
+        check(
+            stdin,
+            "[ERROR] token contains invalid characters.
 Only printable ISO-8859-1 characters are allowed as it is sent in a HTTPS header.",
-    );
-    check(
-        "\u{0016}",
-        "\
-[ERROR] token contains invalid characters.
-Only printable ISO-8859-1 characters are allowed as it is sent in a HTTPS header.",
-    );
+            101,
+        )
+    };
+    let valid = |stdin: &str| check(stdin, "[LOGIN] token for `crates.io` saved", 0);
+
+    // Update config.json so that the rest of the tests don't need to care
+    // whether or not `Updating` is printed.
     check(
-        "\u{0000}",
+        "test",
         "\
-[ERROR] token contains invalid characters.
-Only printable ISO-8859-1 characters are allowed as it is sent in a HTTPS header.",
+[UPDATING] crates.io index
+[LOGIN] token for `crates.io` saved
+",
+        0,
     );
-    check(
-        "你好",
-        "\
-[ERROR] token contains invalid characters.
-Only printable ISO-8859-1 characters are allowed as it is sent in a HTTPS header.",
+
+    invalid("😄");
+    invalid("\u{0016}");
+    invalid("\u{0000}");
+    invalid("你好");
+    valid("foo\tbar");
+    valid("foo bar");
+    valid(
+        r##"!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~"##,
     );
 }