diff --git a/src/snmalloc/aal/aal.h b/src/snmalloc/aal/aal.h
index 7648444..626cbf6 100644
--- a/src/snmalloc/aal/aal.h
+++ b/src/snmalloc/aal/aal.h
@@ -16,7 +16,7 @@
 #    define SNMALLOC_TICK_USE_CLOCK_GETTIME
 #  endif
 #endif
-#include <cstdint>
+#include <stdint.h>
 #include <utility>
 
 #ifndef SNMALLOC_TICK_USE_CLOCK_GETTIME
diff --git a/src/snmalloc/aal/aal_arm.h b/src/snmalloc/aal/aal_arm.h
index 11013c4..c076ce7 100644
--- a/src/snmalloc/aal/aal_arm.h
+++ b/src/snmalloc/aal/aal_arm.h
@@ -12,7 +12,7 @@
 #  endif
 #endif
 
-#include <cstddef>
+#include <stddef.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/aal/aal_consts.h b/src/snmalloc/aal/aal_consts.h
index 8990a41..7b3d22a 100644
--- a/src/snmalloc/aal/aal_consts.h
+++ b/src/snmalloc/aal/aal_consts.h
@@ -1,5 +1,5 @@
 #pragma once
-#include <cstdint>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/aal/address.h b/src/snmalloc/aal/address.h
index 6c1a760..91cce94 100644
--- a/src/snmalloc/aal/address.h
+++ b/src/snmalloc/aal/address.h
@@ -1,7 +1,7 @@
 #pragma once
 #include "../ds_core/ds_core.h"
 
-#include <cstdint>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/ds/aba.h b/src/snmalloc/ds/aba.h
index be4ef53..b0f67ec 100644
--- a/src/snmalloc/ds/aba.h
+++ b/src/snmalloc/ds/aba.h
@@ -27,7 +27,7 @@ namespace snmalloc
   class ABA
   {
   public:
-    struct alignas(2 * sizeof(std::size_t)) Linked
+    struct alignas(2 * sizeof(size_t)) Linked
     {
       T* ptr{nullptr};
       uintptr_t aba{0};
@@ -43,13 +43,13 @@ namespace snmalloc
       sizeof(Linked) == sizeof(Independent),
       "Expecting identical struct sizes in union");
     static_assert(
-      sizeof(Linked) == (2 * sizeof(std::size_t)),
+      sizeof(Linked) == (2 * sizeof(size_t)),
       "Expecting ABA to be the size of two pointers");
 
   private:
     union
     {
-      alignas(2 * sizeof(std::size_t)) stl::Atomic<Linked> linked;
+      alignas(2 * sizeof(size_t)) stl::Atomic<Linked> linked;
       Independent independent;
     };
 
diff --git a/src/snmalloc/ds_core/bits.h b/src/snmalloc/ds_core/bits.h
index ff481f9..3391e70 100644
--- a/src/snmalloc/ds_core/bits.h
+++ b/src/snmalloc/ds_core/bits.h
@@ -1,7 +1,6 @@
 #pragma once
 
-#include <cstddef>
-#include <limits>
+#include <stddef.h>
 
 // #define USE_LZCNT
 
@@ -9,9 +8,10 @@
 #include "snmalloc/stl/atomic.h"
 #include "snmalloc/stl/type_traits.h"
 
-#include <climits>
-#include <cstdint>
+#include <limits.h>
+#include <stdint.h>
 #if defined(_MSC_VER)
+#  include <intrin.h>
 #  include <intsafe.h>
 #endif
 
@@ -95,15 +95,15 @@ namespace snmalloc
       return BITS - index - 1;
 #  endif
 #else
-      if constexpr (stl::is_same_v<unsigned long, std::size_t>)
+      if constexpr (stl::is_same_v<unsigned long, size_t>)
       {
         return static_cast<size_t>(__builtin_clzl(x));
       }
-      else if constexpr (stl::is_same_v<unsigned long long, std::size_t>)
+      else if constexpr (stl::is_same_v<unsigned long long, size_t>)
       {
         return static_cast<size_t>(__builtin_clzll(x));
       }
-      else if constexpr (stl::is_same_v<unsigned int, std::size_t>)
+      else if constexpr (stl::is_same_v<unsigned int, size_t>)
       {
         return static_cast<size_t>(__builtin_clz(x));
       }
@@ -182,15 +182,15 @@ namespace snmalloc
       return _tzcnt_u32(static_cast<unsigned int>(x));
 #  endif
 #else
-      if constexpr (stl::is_same_v<unsigned long, std::size_t>)
+      if constexpr (stl::is_same_v<unsigned long, size_t>)
       {
         return static_cast<size_t>(__builtin_ctzl(x));
       }
-      else if constexpr (stl::is_same_v<unsigned long long, std::size_t>)
+      else if constexpr (stl::is_same_v<unsigned long long, size_t>)
       {
         return static_cast<size_t>(__builtin_ctzll(x));
       }
-      else if constexpr (stl::is_same_v<unsigned int, std::size_t>)
+      else if constexpr (stl::is_same_v<unsigned int, size_t>)
       {
         return static_cast<size_t>(__builtin_ctz(x));
       }
diff --git a/src/snmalloc/ds_core/defines.h b/src/snmalloc/ds_core/defines.h
index 8c076b9..fa85b68 100644
--- a/src/snmalloc/ds_core/defines.h
+++ b/src/snmalloc/ds_core/defines.h
@@ -1,5 +1,5 @@
 #pragma once
-#include <cstddef>
+#include <stddef.h>
 
 #if defined(_MSC_VER) && !defined(__clang__)
 // 28 is FAST_FAIL_INVALID_BUFFER_ACCESS.  Not using the symbolic constant to
diff --git a/src/snmalloc/ds_core/helpers.h b/src/snmalloc/ds_core/helpers.h
index 0041857..753b8ed 100644
--- a/src/snmalloc/ds_core/helpers.h
+++ b/src/snmalloc/ds_core/helpers.h
@@ -5,7 +5,7 @@
 #include "snmalloc/stl/type_traits.h"
 
 #include <array>
-#include <cstddef>
+#include <stddef.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/ds_core/mitigations.h b/src/snmalloc/ds_core/mitigations.h
index 6e60c9d..4f52008 100644
--- a/src/snmalloc/ds_core/mitigations.h
+++ b/src/snmalloc/ds_core/mitigations.h
@@ -1,7 +1,7 @@
 #pragma once
 #include "defines.h"
 
-#include <cstddef>
+#include <stddef.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/ds_core/redblacktree.h b/src/snmalloc/ds_core/redblacktree.h
index 724e7e1..585c173 100644
--- a/src/snmalloc/ds_core/redblacktree.h
+++ b/src/snmalloc/ds_core/redblacktree.h
@@ -1,8 +1,8 @@
 #pragma once
 
 #include <array>
-#include <cstddef>
-#include <cstdint>
+#include <stddef.h>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/ds_core/seqset.h b/src/snmalloc/ds_core/seqset.h
index 2816825..65b188c 100644
--- a/src/snmalloc/ds_core/seqset.h
+++ b/src/snmalloc/ds_core/seqset.h
@@ -4,7 +4,7 @@
 #include "../ds_core/ds_core.h"
 #include "snmalloc/stl/type_traits.h"
 
-#include <cstdint>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/mem/entropy.h b/src/snmalloc/mem/entropy.h
index 3692907..d05fb36 100644
--- a/src/snmalloc/mem/entropy.h
+++ b/src/snmalloc/mem/entropy.h
@@ -4,7 +4,7 @@
 #include "../pal/pal.h"
 #include "snmalloc/stl/type_traits.h"
 
-#include <cstdint>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/mem/freelist.h b/src/snmalloc/mem/freelist.h
index 07b47e6..75c96f2 100644
--- a/src/snmalloc/mem/freelist.h
+++ b/src/snmalloc/mem/freelist.h
@@ -37,7 +37,7 @@
 #include "entropy.h"
 #include "snmalloc/stl/new.h"
 
-#include <cstdint>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/mem/localalloc.h b/src/snmalloc/mem/localalloc.h
index 946d853..2cdefc8 100644
--- a/src/snmalloc/mem/localalloc.h
+++ b/src/snmalloc/mem/localalloc.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "snmalloc/aal/address.h"
 #if defined(_MSC_VER)
 #  define ALLOCATOR __declspec(allocator) __declspec(restrict)
 #elif __has_attribute(malloc)
@@ -888,8 +889,18 @@ namespace snmalloc
       auto sizeclass = entry.get_sizeclass();
       return snmalloc::remaining_bytes(sizeclass, p);
 #else
-      return reinterpret_cast<size_t>(
-        std::numeric_limits<decltype(p)>::max() - p);
+      constexpr address_t mask = static_cast<address_t>(-1);
+      constexpr bool is_signed = mask < 0;
+      constexpr address_t sign_bit =
+        bits::one_at_bit<address_t>(CHAR_BIT * sizeof(address_t) - 1);
+      if constexpr (is_signed)
+      {
+        return (mask ^ sign_bit) - p;
+      }
+      else
+      {
+        return mask - p;
+      }
 #endif
     }
 
diff --git a/src/snmalloc/mem/ticker.h b/src/snmalloc/mem/ticker.h
index 2bce041..c48ff19 100644
--- a/src/snmalloc/mem/ticker.h
+++ b/src/snmalloc/mem/ticker.h
@@ -2,7 +2,7 @@
 
 #include "../ds_core/ds_core.h"
 
-#include <cstdint>
+#include <stdint.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/override/jemalloc_compat.cc b/src/snmalloc/override/jemalloc_compat.cc
index 79206fe..0f47845 100644
--- a/src/snmalloc/override/jemalloc_compat.cc
+++ b/src/snmalloc/override/jemalloc_compat.cc
@@ -1,6 +1,7 @@
 #include "override.h"
 
 #include <errno.h>
+#include <limits.h>
 #include <string.h>
 
 using namespace snmalloc;
@@ -182,7 +183,7 @@ extern "C"
       return allocm_err_not_moved;
     }
 
-    if (std::numeric_limits<size_t>::max() - size > extra)
+    if (SIZE_MAX - size > extra)
     {
       alloc_size = f.aligned_size(size + extra);
     }
diff --git a/src/snmalloc/override/rust.cc b/src/snmalloc/override/rust.cc
index 4a5dcda..980ba8d 100644
--- a/src/snmalloc/override/rust.cc
+++ b/src/snmalloc/override/rust.cc
@@ -1,7 +1,7 @@
 #define SNMALLOC_NAME_MANGLE(a) sn_##a
 #include "snmalloc/snmalloc.h"
 
-#include <cstring>
+#include <string.h>
 
 #ifndef SNMALLOC_EXPORT
 #  define SNMALLOC_EXPORT
@@ -39,7 +39,7 @@ extern "C" SNMALLOC_EXPORT void* SNMALLOC_NAME_MANGLE(rust_realloc)(
   void* p = ThreadAlloc::get().alloc(aligned_new_size);
   if (p)
   {
-    std::memcpy(p, ptr, old_size < new_size ? old_size : new_size);
+    memcpy(p, ptr, old_size < new_size ? old_size : new_size);
     ThreadAlloc::get().dealloc(ptr, aligned_old_size);
   }
   return p;
diff --git a/src/snmalloc/pal/pal_concept.h b/src/snmalloc/pal/pal_concept.h
index 469c8f3..b4b7d87 100644
--- a/src/snmalloc/pal/pal_concept.h
+++ b/src/snmalloc/pal/pal_concept.h
@@ -30,8 +30,8 @@ namespace snmalloc
   template<typename PAL>
   concept IsPAL_static_sizes =
     requires() {
-      typename stl::integral_constant<std::size_t, PAL::address_bits>;
-      typename stl::integral_constant<std::size_t, PAL::page_size>;
+      typename stl::integral_constant<size_t, PAL::address_bits>;
+      typename stl::integral_constant<size_t, PAL::page_size>;
     };
 
   /**
@@ -48,7 +48,7 @@ namespace snmalloc
    * PALs expose a basic library of memory operations.
    */
   template<typename PAL>
-  concept IsPAL_memops = requires(void* vp, std::size_t sz) {
+  concept IsPAL_memops = requires(void* vp, size_t sz) {
                            {
                              PAL::notify_not_using(vp, sz)
                              } noexcept -> ConceptSame<void>;
@@ -72,7 +72,7 @@ namespace snmalloc
    * Absent any feature flags, the PAL must support a crude primitive allocator
    */
   template<typename PAL>
-  concept IsPAL_reserve = requires(PAL p, std::size_t sz) {
+  concept IsPAL_reserve = requires(PAL p, size_t sz) {
                             {
                               PAL::reserve(sz)
                               } noexcept -> ConceptSame<void*>;
@@ -82,7 +82,7 @@ namespace snmalloc
    * Some PALs expose a richer allocator which understands aligned allocations
    */
   template<typename PAL>
-  concept IsPAL_reserve_aligned = requires(std::size_t sz) {
+  concept IsPAL_reserve_aligned = requires(size_t sz) {
                                     {
                                       PAL::template reserve_aligned<true>(sz)
                                       } noexcept -> ConceptSame<void*>;
diff --git a/src/snmalloc/pal/pal_noalloc.h b/src/snmalloc/pal/pal_noalloc.h
index 49b0d4b..590aefe 100644
--- a/src/snmalloc/pal/pal_noalloc.h
+++ b/src/snmalloc/pal/pal_noalloc.h
@@ -8,7 +8,7 @@
 #include "pal_consts.h"
 #include "pal_timer_default.h"
 
-#include <cstring>
+#include <string.h>
 
 namespace snmalloc
 {
diff --git a/src/snmalloc/pal/pal_posix.h b/src/snmalloc/pal/pal_posix.h
index bbbc658..0d50f36 100644
--- a/src/snmalloc/pal/pal_posix.h
+++ b/src/snmalloc/pal/pal_posix.h
@@ -5,17 +5,18 @@
 #if defined(SNMALLOC_BACKTRACE_HEADER)
 #  include SNMALLOC_BACKTRACE_HEADER
 #endif
-#include <cstdlib>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <strings.h>
 #include <sys/mman.h>
 #include <sys/uio.h>
 #include <unistd.h>
 #include <utility>
+
 #if __has_include(<sys/random.h>)
 #  include <sys/random.h>
 #endif
diff --git a/src/test/func/jemalloc/jemalloc.cc b/src/test/func/jemalloc/jemalloc.cc
index 5baddd7..0e34e1f 100644
--- a/src/test/func/jemalloc/jemalloc.cc
+++ b/src/test/func/jemalloc/jemalloc.cc
@@ -1,4 +1,5 @@
 #include <functional>
+#include <limits.h>
 #include <stdio.h>
 #include <test/helpers.h>
 #include <test/setup.h>
@@ -288,7 +289,7 @@ namespace
   {
     START_TEST("allocm out-of-memory behaviour");
     void* ptr = nullptr;
-    int ret = Allocm(&ptr, nullptr, std::numeric_limits<size_t>::max() / 2, 0);
+    int ret = Allocm(&ptr, nullptr, SIZE_MAX / 2, 0);
     EXPECT(
       (ptr == nullptr) && (ret == OUR_ALLOCM_ERR_OOM),
       "Expected massive allocation to fail with out of memory ({}), received "