diff --git a/lib/purescript-cst/src/Language/PureScript/CST/Errors.hs b/lib/purescript-cst/src/Language/PureScript/CST/Errors.hs
index 18ed7079ee..391d42255d 100644
--- a/lib/purescript-cst/src/Language/PureScript/CST/Errors.hs
+++ b/lib/purescript-cst/src/Language/PureScript/CST/Errors.hs
@@ -53,6 +53,7 @@ data ParserErrorType
   | ErrQualifiedName
   | ErrEmptyDo
   | ErrLexeme (Maybe String) [String]
+  | ErrQualifierLexeme Char
   | ErrEof
   | ErrCustom String
   deriving (Show, Eq, Ord)
@@ -128,6 +129,10 @@ prettyPrintErrorMessage (ParserErrorInfo {..}) = case errType of
     "Illegal whitespace character " <> displayCodePoint hd
   ErrLexeme (Just a) _ ->
     "Unexpected " <> a
+  ErrQualifierLexeme hd | isSpace hd ->
+    "Unexpected whitespace character " <> displayCodePoint hd <> ", expected qualifier"
+  ErrQualifierLexeme a ->
+    "Unexpected " <> [ a ] <> ", expected qualifier"
   ErrLineFeedInString ->
     "Unexpected line feed in string literal"
   ErrAstralCodePointInChar ->
diff --git a/lib/purescript-cst/src/Language/PureScript/CST/Lexer.hs b/lib/purescript-cst/src/Language/PureScript/CST/Lexer.hs
index 2ad7646479..a0e7ac0600 100644
--- a/lib/purescript-cst/src/Language/PureScript/CST/Lexer.hs
+++ b/lib/purescript-cst/src/Language/PureScript/CST/Lexer.hs
@@ -357,7 +357,7 @@ token = peek >>= maybe (pure TokEof) k0
             | Char.isUpper ch2 -> next *> upper qual' ch2
             | isIdentStart ch2 -> next *> lower qual' ch2
             | isSymbolChar ch2 -> next *> operator qual' [ch2]
-            | otherwise -> throw $ ErrLexeme (Just [ch2]) []
+            | otherwise -> throw $ ErrQualifierLexeme ch2
           Nothing ->
             throw ErrEof
       _ ->