diff --git a/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-i.js b/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-i.js
new file mode 100644
index 0000000000..10e1883996
--- /dev/null
+++ b/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-i.js
@@ -0,0 +1,19 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Source text cannot use unicode escape sequences to express code points "i", "m", "s" (regular expression flags)
+esid: sec-patterns-static-semantics-early-errors
+features: [regexp-modifiers]
+negative:
+  phase: parse
+  type: SyntaxError
+info: |
+    Atom :: ( ? RegularExpresisonFlags : Disjunction )
+    It is a Syntax Error if the source text matched by RegularExpressionFlags contains any code points other than "i", "m", "s", or if it contains the same code point more than once.
+
+---*/
+
+$DONOTEVALUATE();
+
+/(?\u0069:a)/u /* i */;
diff --git a/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-m.js b/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-m.js
new file mode 100644
index 0000000000..4916997fbf
--- /dev/null
+++ b/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-m.js
@@ -0,0 +1,19 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Source text cannot use unicode escape sequences to express code points "i", "m", "s" (regular expression flags)
+esid: sec-patterns-static-semantics-early-errors
+features: [regexp-modifiers]
+negative:
+  phase: parse
+  type: SyntaxError
+info: |
+    Atom :: ( ? RegularExpresisonFlags : Disjunction )
+    It is a Syntax Error if the source text matched by RegularExpressionFlags contains any code points other than "i", "m", "s", or if it contains the same code point more than once.
+
+---*/
+
+$DONOTEVALUATE();
+
+/(?\u006D:a)/u /* m */;
diff --git a/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-s.js b/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-s.js
new file mode 100644
index 0000000000..4e91d5bb51
--- /dev/null
+++ b/test/language/literals/regexp/early-err-modifiers-should-not-unicode-escape-s.js
@@ -0,0 +1,19 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Source text cannot use unicode escape sequences to express code points "i", "m", "s" (regular expression flags)
+esid: sec-patterns-static-semantics-early-errors
+features: [regexp-modifiers]
+negative:
+  phase: parse
+  type: SyntaxError
+info: |
+    Atom :: ( ? RegularExpresisonFlags : Disjunction )
+    It is a Syntax Error if the source text matched by RegularExpressionFlags contains any code points other than "i", "m", "s", or if it contains the same code point more than once.
+
+---*/
+
+$DONOTEVALUATE();
+
+/(?\u0073:a)/u /* s */;