diff --git a/packages/parser/src/language/common/common.langium b/packages/parser/src/language/common/common.langium
index baf933e0fc..7989de1931 100644
--- a/packages/parser/src/language/common/common.langium
+++ b/packages/parser/src/language/common/common.langium
@@ -13,9 +13,9 @@ fragment EOL returns string:
 ;
 
 terminal NEWLINE: /\r?\n/;
-terminal ACC_DESCR: /accDescr([\t ]*:[^\n\r]*(?=%%)|\s*{[^}]*})|accDescr([\t ]*:[^\n\r]*|\s*{[^}]*})/;
-terminal ACC_TITLE: /accTitle[\t ]*:[^\n\r]*(?=%%)|accTitle[\t ]*:[^\n\r]*/;
-terminal TITLE: /title([\t ][^\n\r]*|)(?=%%)|title([\t ][^\n\r]*|)/;
+terminal ACC_DESCR: /[\t ]*accDescr(?:[\t ]*:([^\n\r]*?(?=%%)|[^\n\r]*)|\s*{([^}]*)})/;
+terminal ACC_TITLE: /[\t ]*accTitle[\t ]*:(?:[^\n\r]*?(?=%%)|[^\n\r]*)/;
+terminal TITLE: /[\t ]*title(?:[\t ][^\n\r]*?(?=%%)|[\t ][^\n\r]*|)/;
 
 hidden terminal WHITESPACE: /[\t ]+/;
 hidden terminal YAML: /---[\t ]*\r?\n(?:[\S\s]*?\r?\n)?---(?:\r?\n|(?!\S))/;