diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
index 116cf3b6..79136530 100644
--- a/include/fmt/ranges.h
+++ b/include/fmt/ranges.h
@@ -244,7 +244,7 @@ inline auto check(uint16_t x, const singleton* singletonuppers,
     if (xupper < su.upper) break;
     if (xupper == su.upper) {
       for (auto j = lowerstart; j < lowerend; ++j) {
-        if (singletonlowers[j] == x) return false;
+        if (singletonlowers[j] == (x & 0xff)) return false;
       }
     }
     lowerstart = lowerend;
@@ -254,7 +254,7 @@ inline auto check(uint16_t x, const singleton* singletonuppers,
   auto current = true;
   for (size_t i = 0; i < normal_size; ++i) {
     auto v = static_cast<int>(normal[i]);
-    auto len = (v & 0x80) != 0 ? (v & 0x7f) << 8 | normal[i++] : v;
+    auto len = (v & 0x80) != 0 ? (v & 0x7f) << 8 | normal[++i] : v;
     xsigned -= len;
     if (xsigned < 0) break;
     current = !current;
diff --git a/support/printable.py b/support/printable.py
index 192e89d6..ccb36e11 100755
--- a/support/printable.py
+++ b/support/printable.py
@@ -171,41 +171,6 @@ def main():
     normal1 = compress_normal(normal1)
 
     print("""\
-struct singleton {
-  unsigned char upper;
-  unsigned char lowercount;
-};
-
-inline auto check(uint16_t x, const singleton* singletonuppers,
-                  size_t singletonuppers_size,
-                  const unsigned char* singletonlowers,
-                  const unsigned char* normal, size_t normal_size) -> bool {
-  auto xupper = x >> 8;
-  auto lowerstart = 0;
-  for (size_t i = 0; i < singletonuppers_size; ++i) {
-    auto su = singletonuppers[i];
-    auto lowerend = lowerstart + su.lowercount;
-    if (xupper < su.upper) break;
-    if (xupper == su.upper) {
-      for (auto j = lowerstart; j < lowerend; ++j) {
-        if (singletonlowers[j] == x) return false;
-      }
-    }
-    lowerstart = lowerend;
-  }
-
-  auto xsigned = static_cast<int>(x);
-  auto current = true;
-  for (size_t i = 0; i < normal_size; ++i) {
-    auto v = static_cast<int>(normal[i]);
-    auto len = v & 0x80 != 0 ? (v & 0x7f) << 8 | normal[i++] : v;
-    xsigned -= len;
-    if (xsigned < 0) break;
-    current = !current;
-  }
-  return current;
-}
-
 inline auto is_printable(uint32_t cp) -> bool {\
 """)
     print_singletons(singletons0u, singletons0l, 'singletons0u', 'singletons0l')
diff --git a/test/ranges-test.cc b/test/ranges-test.cc
index 1addbf5f..1d908b40 100644
--- a/test/ranges-test.cc
+++ b/test/ranges-test.cc
@@ -263,6 +263,12 @@ TEST(ranges_test, join_range) {
 }
 #endif  // FMT_RANGES_TEST_ENABLE_JOIN
 
+TEST(ranges_test, is_printable) {
+  using fmt::detail::is_printable;
+  EXPECT_TRUE(is_printable(0x0323));
+  EXPECT_FALSE(is_printable(0x0378));
+}
+
 TEST(ranges_test, escape_string) {
   using vec = std::vector<std::string>;
   EXPECT_EQ(fmt::format("{}", vec{"\n\r\t\"\\"}), "[\"\\n\\r\\t\\\"\\\\\"]");