diff --git a/json/internal_types.mbt b/json/internal_types.mbt
index 89653efbb5..9d48099be8 100644
--- a/json/internal_types.mbt
+++ b/json/internal_types.mbt
@@ -33,32 +33,6 @@ fn ParseContext::make(
   }
 }
 
-///|
-priv struct CharClass(Array[(Char, Char)])
-
-///|
-fn CharClass::of(array : Array[(Char, Char)]) -> CharClass {
-  CharClass(array)
-}
-
-///|
-fn CharClass::contains(self : CharClass, c : Char) -> Bool {
-  let CharClass(self) = self
-  for left = 0, right = self.length(); left < right; {
-    let middle = (left + right) / 2
-    let (min, max) = self[middle]
-    if c < min {
-      continue left, middle
-    } else if c > max {
-      continue middle + 1, right
-    } else {
-      break true
-    }
-  } else {
-    false
-  }
-}
-
 ///|
 priv enum Token {
   Null
diff --git a/json/internal_types_wbtest.mbt b/json/internal_types_wbtest.mbt
deleted file mode 100644
index eee8f0e2e2..0000000000
--- a/json/internal_types_wbtest.mbt
+++ /dev/null
@@ -1,42 +0,0 @@
-// Copyright 2026 International Digital Economy Academy
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-///|
-test "CharClass::contains/simple_case" {
-  let char_class = CharClass::of([('a', 'z')])
-  inspect(char_class.contains('a'), content=true)
-  inspect(char_class.contains('m'), content=true)
-  inspect(char_class.contains('z'), content=true)
-  inspect(char_class.contains('A'), content=false)
-}
-
-///|
-test "CharClass::contains/multiple_ranges" {
-  let char_class = CharClass::of([('a', 'f'), ('m', 'r'), ('x', 'z')])
-  inspect(char_class.contains('a'), content=true)
-  inspect(char_class.contains('p'), content=true)
-  inspect(char_class.contains('y'), content=true)
-  inspect(char_class.contains('g'), content=false)
-  inspect(char_class.contains('w'), content=false)
-}
-
-///|
-test "CharClass::contains/boundary_case" {
-  let char_class = CharClass::of([('a', 'c'), ('e', 'h')])
-  inspect(char_class.contains('a'), content=true)
-  inspect(char_class.contains('c'), content=true)
-  inspect(char_class.contains('e'), content=true)
-  inspect(char_class.contains('h'), content=true)
-  inspect(char_class.contains('d'), content=false)
-}
diff --git a/json/lex_main.mbt b/json/lex_main.mbt
index 8d9ff1c91c..85df30256f 100644
--- a/json/lex_main.mbt
+++ b/json/lex_main.mbt
@@ -12,18 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-///|
-let non_ascii_whitespace : CharClass = CharClass::of([
-  ('\u00A0', '\u00A0'),
-  ('\u1680', '\u1680'),
-  ('\u2000', '\u200A'),
-  ('\u2028', '\u2029'),
-  ('\u202F', '\u202F'),
-  ('\u205F', '\u205F'),
-  ('\u3000', '\u3000'),
-  ('\uFEFF', '\uFEFF'),
-])
-
 ///|
 fn ParseContext::lex_value(
   ctx : ParseContext,
@@ -87,9 +75,6 @@ fn ParseContext::lex_value(
         return String(s)
       }
       Some(c) => {
-        if c > '\u{7f}' && non_ascii_whitespace.contains(c) {
-          continue
-        }
         let shift = -c.utf16_len()
         ctx.invalid_char(shift~)
       }
diff --git a/json/lex_misc.mbt b/json/lex_misc.mbt
index 577606d073..21ae9e3bef 100644
--- a/json/lex_misc.mbt
+++ b/json/lex_misc.mbt
@@ -118,10 +118,7 @@ fn ParseContext::lex_skip_whitespace(ctx : ParseContext) -> Unit {
   for {
     match ctx.read_char() {
       Some('\t' | ' ' | '\n' | '\r') => continue
-      Some(c) => {
-        if c > '\u{7f}' && non_ascii_whitespace.contains(c) {
-          continue
-        }
+      Some(_) => {
         ctx.offset -= 1
         break
       }
diff --git a/json/parse_error_test.mbt b/json/parse_error_test.mbt
index 7e81dd83c2..eda65f3494 100644
--- a/json/parse_error_test.mbt
+++ b/json/parse_error_test.mbt
@@ -24,7 +24,9 @@ test "parse error branches" {
   guard (try? @json.parse("nullx")) is Err(InvalidChar(_, _)) else {
     fail("expected InvalidChar for trailing data")
   }
-  inspect(@json.parse("\u{00A0}null"), content="Null")
+  guard (try? @json.parse("\u{00A0}null")) is Err(InvalidChar(_, _)) else {
+    fail("expected InvalidChar for leading non-breaking space")
+  }
   guard (try? @json.parse("tx")) is Err(InvalidChar(_, _)) else {
     fail("expected InvalidChar for invalid literal")
   }
diff --git a/json/parse_test.mbt b/json/parse_test.mbt
index d89a90778f..cfe93ab2c6 100644
--- a/json/parse_test.mbt
+++ b/json/parse_test.mbt
@@ -222,7 +222,7 @@ test "parses escaped characters" {
 
 ///|
 test "parses whitespace" {
-  let json = test_parse("{\t \u00A0\uFEFF\n\r\u2028\u2029\u2003}")
+  let json = test_parse("{\t \n\r}")
   assert_eq(json, Json::object({}))
 }
 //endregion