diff --git a/crates/parser/src/lexed_str.rs b/crates/parser/src/lexed_str.rs
index b9e7566fdf9bc..3753a1beb7a8e 100644
--- a/crates/parser/src/lexed_str.rs
+++ b/crates/parser/src/lexed_str.rs
@@ -371,6 +371,7 @@ fn error_to_diagnostic_message(error: EscapeError, mode: Mode) -> &'static str {
             "non-ASCII character in byte string literal"
         }
         EscapeError::NonAsciiCharInByte => "non-ASCII character in raw byte string literal",
+        EscapeError::NulInCStr => "null character in C string literal",
         EscapeError::UnskippedWhitespaceWarning => "",
         EscapeError::MultipleSkippedLinesWarning => "",
     }
diff --git a/crates/syntax/src/validation.rs b/crates/syntax/src/validation.rs
index eabbda2c3983c..0504f67c9dc7e 100644
--- a/crates/syntax/src/validation.rs
+++ b/crates/syntax/src/validation.rs
@@ -106,6 +106,9 @@ fn rustc_unescape_error_to_string(err: unescape::EscapeError) -> (&'static str,
         EE::NonAsciiCharInByte  => {
             "Byte literals must not contain non-ASCII characters"
         }
+        EE::NulInCStr  => {
+            "C strings literals must not contain null characters"
+        }
         EE::UnskippedWhitespaceWarning => "Whitespace after this escape is not skipped",
         EE::MultipleSkippedLinesWarning => "Multiple lines are skipped by this escape",