diff --git a/src/pyk/kast/outer_lexer.py b/src/pyk/kast/outer_lexer.py
index ce33539e4..015d9de04 100644
--- a/src/pyk/kast/outer_lexer.py
+++ b/src/pyk/kast/outer_lexer.py
@@ -113,8 +113,9 @@ class Token(NamedTuple):
 _DIGIT: Final = set('0123456789')
 _LOWER: Final = set('abcdefghijklmnopqrstuvwxyz')
 _UPPER: Final = set('ABCDEFGHIJKLMNOPQRSTUVWXYZ')
-_ALPHA: Final = set().union(_LOWER).union(_UPPER)
-_ALNUM: Final = set(_ALPHA).union(_DIGIT)
+_ALPHA: Final = _LOWER.union(_UPPER)
+_ALNUM: Final = _ALPHA.union(_DIGIT)
+_WORD: Final = {'_'}.union(_ALNUM)
 
 
 class State(Enum):
@@ -456,29 +457,42 @@ def _hash_upper_id(la: str, it: Iterator[str]) -> tuple[Token, str]:
 
 
 _MODNAME_KEYWORDS: Final = {'private', 'public'}
-_MODNAME_CHARS: Final = {'-', '_'}.union(_ALNUM)
 
 
 def _modname(la: str, it: Iterator) -> tuple[Token, str]:
+    r"""[a-zA-Z]\w*(-\w+)*"""
+
     la = _skip_ws_and_comments(la, it)
 
     consumed = []
 
-    if la == '#':
+    if la not in _ALPHA:
+        raise _unexpected_character(la)
+
+    consumed.append(la)
+    la = next(it, '')
+
+    while la in _WORD:
         consumed.append(la)
         la = next(it, '')
 
-    if not la:
-        raise _unexpected_character(la)
+    while True:
+        if la != '-':
+            break
+
+        consumed.append(la)
+        la = next(it, '')
 
-    allow_dash = False
-    while la in _MODNAME_CHARS:
-        if la == '-' and not allow_dash:
+        if la not in _WORD:
             raise _unexpected_character(la)
-        allow_dash = la != '-'
+
         consumed.append(la)
         la = next(it, '')
 
+        while la in _WORD:
+            consumed.append(la)
+            la = next(it, '')
+
     text = ''.join(consumed)
     if text in _MODNAME_KEYWORDS:
         return _KEYWORDS[text], la
diff --git a/src/tests/unit/kast/test_outer_lexer.py b/src/tests/unit/kast/test_outer_lexer.py
index 9550bec55..923fd8c54 100644
--- a/src/tests/unit/kast/test_outer_lexer.py
+++ b/src/tests/unit/kast/test_outer_lexer.py
@@ -304,10 +304,8 @@ def test_default(text: str, expected_token: Token, expected_remaining: str) -> N
     ('private MODULE', Token('private', TokenType.KW_PRIVATE), ' MODULE'),
     ('public', Token('public', TokenType.KW_PUBLIC), ''),
     ('module', Token('module', TokenType.MODNAME), ''),
-    ('module ', Token('module', TokenType.MODNAME), ' '),
     ('MODULE', Token('MODULE', TokenType.MODNAME), ''),
-    ('#module', Token('#module', TokenType.MODNAME), ''),
-    ('#module#module', Token('#module', TokenType.MODNAME), '#module'),
+    ('module#module', Token('module', TokenType.MODNAME), '#module'),
     ('mo-du-le', Token('mo-du-le', TokenType.MODNAME), ''),
     ('m0-DU_l3', Token('m0-DU_l3', TokenType.MODNAME), ''),
     ('TEST-MODULE', Token('TEST-MODULE', TokenType.MODNAME), ''),