diff --git a/include/nlohmann/detail/conversions/to_chars.hpp b/include/nlohmann/detail/conversions/to_chars.hpp
index 186b62ef1..93837baa6 100644
--- a/include/nlohmann/detail/conversions/to_chars.hpp
+++ b/include/nlohmann/detail/conversions/to_chars.hpp
@@ -196,7 +196,7 @@ boundaries compute_boundaries(FloatType value)
     constexpr int      kMinExp    = 1 - kBias;
     constexpr uint64_t kHiddenBit = uint64_t{1} << (kPrecision - 1); // = 2^(p-1)
 
-    using bits_type = typename std::conditional< kPrecision == 24, uint32_t, uint64_t >::type;
+    using bits_type = typename std::conditional<kPrecision == 24, uint32_t, uint64_t>::type;
 
     const uint64_t bits = reinterpret_bits<bits_type>(value);
     const uint64_t E = bits >> (kPrecision - 1);
@@ -607,7 +607,10 @@ inline void grisu2_digit_gen(char* buffer, int& length, int& decimal_exponent,
     //         = ((p1        ) * 2^-e + (p2        )) * 2^e
     //         = p1 + p2 * 2^e
 
-    const diyfp one(uint64_t{1} << -M_plus.e, M_plus.e);
+    const diyfp one(uint64_t
+    {
+        1
+    } << -M_plus.e, M_plus.e);
 
     uint32_t p1 = static_cast<uint32_t>(M_plus.f >> -one.e); // p1 = f div 2^-e (Since -e >= 32, p1 fits into a 32-bit int.)
     uint64_t p2 = M_plus.f & (one.f - 1);                    // p2 = f mod 2^-e
diff --git a/include/nlohmann/detail/output/serializer.hpp b/include/nlohmann/detail/output/serializer.hpp
index 19ab9894a..c0f817766 100644
--- a/include/nlohmann/detail/output/serializer.hpp
+++ b/include/nlohmann/detail/output/serializer.hpp
@@ -414,7 +414,7 @@ class serializer
         else
         {
             // we finish reading, but do not accept: string was incomplete
-            std::string sn(3,'\0');
+            std::string sn(3, '\0');
             snprintf(&sn[0], sn.size(), "%.2X", static_cast<uint8_t>(s.back()));
             JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + sn));
         }
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index f5b93632f..dedd2edc2 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -7667,7 +7667,7 @@ struct hash<nlohmann::json>
 /// @note: do not remove the space after '<',
 ///        see https://github.com/nlohmann/json/pull/679
 template<>
-struct less< ::nlohmann::detail::value_t>
+struct less<::nlohmann::detail::value_t>
 {
     /*!
     @brief compare two value_t enum values
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 2b387a8b6..5191b474d 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -1973,10 +1973,8 @@ class input_adapter
 #include <clocale> // localeconv
 #include <cstddef> // size_t
 #include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
+#include <cstdio> // snprintf
 #include <initializer_list> // initializer_list
-#include <ios> // hex, uppercase
-#include <iomanip> // setw, setfill
-#include <sstream> // stringstream
 #include <string> // char_traits, string
 #include <vector> // vector
 
@@ -3146,10 +3144,9 @@ scan_number_done:
             if ('\x00' <= c and c <= '\x1F')
             {
                 // escape control characters
-                std::stringstream ss;
-                ss << "<U+" << std::setw(4) << std::uppercase << std::setfill('0')
-                   << std::hex << static_cast<int>(c) << ">";
-                result += ss.str();
+                char cs[9];
+                snprintf(cs, 9, "<U+%.4X>", c);
+                result += cs;
             }
             else
             {
@@ -5619,12 +5616,10 @@ class output_adapter
 #include <cmath> // ldexp
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
+#include <cstdio> // snprintf
 #include <cstring> // memcpy
-#include <iomanip> // setw, setfill
-#include <ios> // hex
 #include <iterator> // back_inserter
 #include <limits> // numeric_limits
-#include <sstream> // stringstream
 #include <string> // char_traits, string
 #include <utility> // make_pair, move
 
@@ -7283,9 +7278,9 @@ class binary_reader
     */
     std::string get_token_string() const
     {
-        std::stringstream ss;
-        ss << std::setw(2) << std::uppercase << std::setfill('0') << std::hex << current;
-        return ss.str();
+        char cr[3];
+        snprintf(cr, 3, "%.2X", current);
+        return std::string{cr};
     }
 
   private:
@@ -8272,11 +8267,8 @@ class binary_writer
 #include <cstddef> // size_t, ptrdiff_t
 #include <cstdint> // uint8_t
 #include <cstdio> // snprintf
-#include <iomanip> // setfill
-#include <iterator> // next
 #include <limits> // numeric_limits
 #include <string> // string
-#include <sstream> // stringstream
 #include <type_traits> // is_same
 
 // #include <nlohmann/detail/exceptions.hpp>
@@ -8480,7 +8472,7 @@ boundaries compute_boundaries(FloatType value)
     constexpr int      kMinExp    = 1 - kBias;
     constexpr uint64_t kHiddenBit = uint64_t{1} << (kPrecision - 1); // = 2^(p-1)
 
-    using bits_type = typename std::conditional< kPrecision == 24, uint32_t, uint64_t >::type;
+    using bits_type = typename std::conditional<kPrecision == 24, uint32_t, uint64_t>::type;
 
     const uint64_t bits = reinterpret_bits<bits_type>(value);
     const uint64_t E = bits >> (kPrecision - 1);
@@ -8891,7 +8883,10 @@ inline void grisu2_digit_gen(char* buffer, int& length, int& decimal_exponent,
     //         = ((p1        ) * 2^-e + (p2        )) * 2^e
     //         = p1 + p2 * 2^e
 
-    const diyfp one(uint64_t{1} << -M_plus.e, M_plus.e);
+    const diyfp one(uint64_t
+    {
+        1
+    } << -M_plus.e, M_plus.e);
 
     uint32_t p1 = static_cast<uint32_t>(M_plus.f >> -one.e); // p1 = f div 2^-e (Since -e >= 32, p1 fits into a 32-bit int.)
     uint64_t p2 = M_plus.f & (one.f - 1);                    // p2 = f mod 2^-e
@@ -9753,9 +9748,9 @@ class serializer
 
                 case UTF8_REJECT:  // decode found invalid UTF-8 byte
                 {
-                    std::stringstream ss;
-                    ss << std::setw(2) << std::uppercase << std::setfill('0') << std::hex << static_cast<int>(byte);
-                    JSON_THROW(type_error::create(316, "invalid UTF-8 byte at index " + std::to_string(i) + ": 0x" + ss.str()));
+                    std::string sn(3, '\0');
+                    snprintf(&sn[0], sn.size(), "%.2X", byte);
+                    JSON_THROW(type_error::create(316, "invalid UTF-8 byte at index " + std::to_string(i) + ": 0x" + sn));
                 }
 
                 default:  // decode found yet incomplete multi-byte code point
@@ -9781,9 +9776,9 @@ class serializer
         else
         {
             // we finish reading, but do not accept: string was incomplete
-            std::stringstream ss;
-            ss << std::setw(2) << std::uppercase << std::setfill('0') << std::hex << static_cast<int>(static_cast<uint8_t>(s.back()));
-            JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + ss.str()));
+            std::string sn(3, '\0');
+            snprintf(&sn[0], sn.size(), "%.2X", static_cast<uint8_t>(s.back()));
+            JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + sn));
         }
     }
 
@@ -18411,7 +18406,7 @@ struct hash<nlohmann::json>
 /// @note: do not remove the space after '<',
 ///        see https://github.com/nlohmann/json/pull/679
 template<>
-struct less< ::nlohmann::detail::value_t>
+struct less<::nlohmann::detail::value_t>
 {
     /*!
     @brief compare two value_t enum values
diff --git a/test/src/unit-conversions.cpp b/test/src/unit-conversions.cpp
index 79ccf6810..0e1a4874c 100644
--- a/test/src/unit-conversions.cpp
+++ b/test/src/unit-conversions.cpp
@@ -1093,9 +1093,9 @@ TEST_CASE("value conversion")
 
                 SECTION("superfluous entries")
                 {
-                  json j8 = {{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
-                  m2 = j8.get<std::map<int, int>>();
-                  CHECK(m == m2);
+                    json j8 = {{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
+                    m2 = j8.get<std::map<int, int>>();
+                    CHECK(m == m2);
                 }
             }
 
diff --git a/test/src/unit-inspection.cpp b/test/src/unit-inspection.cpp
index 4c03cf968..e50c7338e 100644
--- a/test/src/unit-inspection.cpp
+++ b/test/src/unit-inspection.cpp
@@ -317,8 +317,8 @@ TEST_CASE("object inspection")
     SECTION("round trips")
     {
         for (const auto& s :
-                {"3.141592653589793", "1000000000000000010E5"
-                })
+    {"3.141592653589793", "1000000000000000010E5"
+    })
         {
             json j1 = json::parse(s);
             std::string s1 = j1.dump();
diff --git a/test/src/unit-noexcept.cpp b/test/src/unit-noexcept.cpp
index 2d49b3272..358d6bb93 100644
--- a/test/src/unit-noexcept.cpp
+++ b/test/src/unit-noexcept.cpp
@@ -45,19 +45,19 @@ void from_json(const json&, pod) noexcept;
 void from_json(const json&, pod_bis);
 static json j;
 
-static_assert(noexcept(json{}), "");
+static_assert(noexcept(json {}), "");
 static_assert(noexcept(nlohmann::to_json(j, 2)), "");
 static_assert(noexcept(nlohmann::to_json(j, 2.5)), "");
 static_assert(noexcept(nlohmann::to_json(j, true)), "");
-static_assert(noexcept(nlohmann::to_json(j, test{})), "");
-static_assert(noexcept(nlohmann::to_json(j, pod{})), "");
-static_assert(not noexcept(nlohmann::to_json(j, pod_bis{})), "");
+static_assert(noexcept(nlohmann::to_json(j, test {})), "");
+static_assert(noexcept(nlohmann::to_json(j, pod {})), "");
+static_assert(not noexcept(nlohmann::to_json(j, pod_bis {})), "");
 static_assert(noexcept(json(2)), "");
-static_assert(noexcept(json(test{})), "");
-static_assert(noexcept(json(pod{})), "");
+static_assert(noexcept(json(test {})), "");
+static_assert(noexcept(json(pod {})), "");
 static_assert(noexcept(j.get<pod>()), "");
 static_assert(not noexcept(j.get<pod_bis>()), "");
-static_assert(noexcept(json(pod{})), "");
+static_assert(noexcept(json(pod {})), "");
 
 TEST_CASE("runtime checks")
 {
diff --git a/test/src/unit-udt.cpp b/test/src/unit-udt.cpp
index 040c3e980..3807d212f 100644
--- a/test/src/unit-udt.cpp
+++ b/test/src/unit-udt.cpp
@@ -585,7 +585,7 @@ struct pod_serializer
                   std::is_pod<U>::value and std::is_class<U>::value, int>::type = 0>
     static void to_json(BasicJsonType& j, const  T& t) noexcept
     {
-        auto bytes = static_cast< const unsigned char*>(static_cast<const void*>(&t));
+        auto bytes = static_cast<const unsigned char*>(static_cast<const void*>(&t));
         std::uint64_t value = bytes[0];
         for (auto i = 1; i < 8; ++i)
             value |= std::uint64_t{bytes[i]} << 8 * i;