diff --git a/crates/improvise-core/src/format.rs b/crates/improvise-core/src/format.rs
index ef5dfb60..cbc1909a 100644
--- a/crates/improvise-core/src/format.rs
+++ b/crates/improvise-core/src/format.rs
@@ -131,6 +131,15 @@ mod tests {
         assert_eq!(parse_number_format(",.999f"), (true, 0));
     }
 
+    /// `format:` is `rest_of_line` in the grammar, so the format string can hold
+    /// any text at all — including a multibyte char right after the dot.
+    #[test]
+    fn a_multibyte_character_after_the_dot_does_not_split_a_char_boundary() {
+        assert_eq!(parse_number_format(",.2\u{20ac}"), (true, 2));
+        assert_eq!(parse_number_format(".\u{20ac}"), (false, 0));
+        assert_eq!(parse_number_format(".\u{0662}"), (false, 0));
+    }
+
     #[test]
     fn a_format_naming_no_precision_at_all_reads_as_zero() {
         assert_eq!(parse_number_format(",f"), (true, 0));