diff --git a/lexer/lexer.go b/lexer/lexer.go
index 8f72a46ec..a8a5736b9 100644
--- a/lexer/lexer.go
+++ b/lexer/lexer.go
@@ -397,7 +397,8 @@ func (l *Lexer) readString(quote rune) Item {
 				val := hexValue(hex1)*16 + hexValue(hex2)
 				sb.WriteByte(byte(val))
 			default:
-				// Unknown escape, just write the character after backslash
+				// Unknown escape, preserve both the backslash and the character
+				sb.WriteRune('\\')
 				sb.WriteRune(l.ch)
 			}
 			l.readChar()
diff --git a/parser/testdata/01497_extract_all_groups_empty_match/metadata.json b/parser/testdata/01497_extract_all_groups_empty_match/metadata.json
index ef120d978..0967ef424 100644
--- a/parser/testdata/01497_extract_all_groups_empty_match/metadata.json
+++ b/parser/testdata/01497_extract_all_groups_empty_match/metadata.json
@@ -1 +1 @@
-{"todo": true}
+{}
diff --git a/parser/testdata/01847_bad_like/metadata.json b/parser/testdata/01847_bad_like/metadata.json
index ef120d978..0967ef424 100644
--- a/parser/testdata/01847_bad_like/metadata.json
+++ b/parser/testdata/01847_bad_like/metadata.json
@@ -1 +1 @@
-{"todo": true}
+{}
diff --git a/parser/testdata/02374_regexp_replace/metadata.json b/parser/testdata/02374_regexp_replace/metadata.json
index ef120d978..0967ef424 100644
--- a/parser/testdata/02374_regexp_replace/metadata.json
+++ b/parser/testdata/02374_regexp_replace/metadata.json
@@ -1 +1 @@
-{"todo": true}
+{}
diff --git a/parser/testdata/02580_like_substring_search_bug/metadata.json b/parser/testdata/02580_like_substring_search_bug/metadata.json
index ef120d978..0967ef424 100644
--- a/parser/testdata/02580_like_substring_search_bug/metadata.json
+++ b/parser/testdata/02580_like_substring_search_bug/metadata.json
@@ -1 +1 @@
-{"todo": true}
+{}
diff --git a/parser/testdata/03031_input_format_allow_errors_num_bad_escape_sequence/metadata.json b/parser/testdata/03031_input_format_allow_errors_num_bad_escape_sequence/metadata.json
index ef120d978..0967ef424 100644
--- a/parser/testdata/03031_input_format_allow_errors_num_bad_escape_sequence/metadata.json
+++ b/parser/testdata/03031_input_format_allow_errors_num_bad_escape_sequence/metadata.json
@@ -1 +1 @@
-{"todo": true}
+{}