diff --git a/src/lexer/regexp.ts b/src/lexer/regexp.ts
index 4a48d504..394099f3 100644
--- a/src/lexer/regexp.ts
+++ b/src/lexer/regexp.ts
@@ -59,13 +59,13 @@ export function scanRegularExpression(parser: ParserState, context: Context): To
   const bodyEnd = parser.index - 1;
 
   const enum RegexFlags {
-    Empty = 0b00000,
-    IgnoreCase = 0b00001,
-    Global = 0b00010,
-    Multiline = 0b00100,
-    Unicode = 0b10000,
-    Sticky = 0b01000,
-    DotAll = 0b1100
+    Empty = 0b000000,
+    IgnoreCase = 0b000001,
+    Global = 0b000010,
+    Multiline = 0b000100,
+    Unicode = 0b010000,
+    Sticky = 0b001000,
+    DotAll = 0b100000
   }
 
   let mask = RegexFlags.Empty;
diff --git a/test/lexer/regexp.ts b/test/lexer/regexp.ts
index 80b4ed5b..34e24e5f 100644
--- a/test/lexer/regexp.ts
+++ b/test/lexer/regexp.ts
@@ -133,6 +133,13 @@ describe('Lexer - Regular expressions', () => {
     [Context.AllowRegExp, '/a(?!b(?!c)d)e/', 'a(?!b(?!c)d)e', ''],
     [Context.AllowRegExp, '/[^a-z]{4}/', '[^a-z]{4}', ''],
     [Context.AllowRegExp, '/1?1/mig', '1?1', 'mig'],
+    [Context.AllowRegExp, '/.*/sm', '.*', 'sm'],
+    [Context.AllowRegExp, '/.*/ms', '.*', 'ms'],
+    [Context.AllowRegExp, '/.*/sy', '.*', 'sy'],
+    [Context.AllowRegExp, '/.*/ys', '.*', 'ys'],
+    [Context.AllowRegExp, '/.*/s', '.*', 's'],
+    [Context.AllowRegExp, '/.*/m', '.*', 'm'],
+    [Context.AllowRegExp, '/.*/y', '.*', 'y'],
     [Context.AllowRegExp, '/\\%([0-9]*)\\[(\\^)?(\\]?[^\\]]*)\\]/', '\\%([0-9]*)\\[(\\^)?(\\]?[^\\]]*)\\]', '']
   ];