diff --git a/src/ds/defines.h b/src/ds/defines.h
index b21b194..7830433 100644
--- a/src/ds/defines.h
+++ b/src/ds/defines.h
@@ -95,6 +95,12 @@
 
 namespace snmalloc
 {
+#ifdef NDEBUG
+  static constexpr bool DEBUG = false;
+#else
+  static constexpr bool DEBUG = true;
+#endif
+
   // Forwards reference so that the platform can define how to handle errors.
   [[noreturn]] SNMALLOC_COLD void error(const char* const str);
 } // namespace snmalloc
@@ -161,12 +167,15 @@ namespace snmalloc
   {
     if (SNMALLOC_UNLIKELY(!test))
     {
-#ifdef NDEBUG
-      UNUSED(str);
-      SNMALLOC_FAST_FAIL();
-#else
-      check_client_error(str);
-#endif
+      if constexpr (DEBUG)
+      {
+        UNUSED(str);
+        SNMALLOC_FAST_FAIL();
+      }
+      else
+      {
+        check_client_error(str);
+      }
     }
   }
 
diff --git a/src/ds/dllist.h b/src/ds/dllist.h
index d4c20e8..95bb8e5 100644
--- a/src/ds/dllist.h
+++ b/src/ds/dllist.h
@@ -92,9 +92,7 @@ namespace snmalloc
 
     void insert(Ptr<T> item)
     {
-#ifndef NDEBUG
       debug_check_not_contains(item);
-#endif
 
       item->next = head;
       item->prev = Terminator();
@@ -105,16 +103,14 @@ namespace snmalloc
         tail = item;
 
       head = item;
-#ifndef NDEBUG
-      debug_check();
-#endif
+
+      if constexpr (DEBUG)
+        debug_check();
     }
 
     void insert_back(Ptr<T> item)
     {
-#ifndef NDEBUG
       debug_check_not_contains(item);
-#endif
 
       item->prev = tail;
       item->next = Terminator();
@@ -125,16 +121,13 @@ namespace snmalloc
         head = item;
 
       tail = item;
-#ifndef NDEBUG
+
       debug_check();
-#endif
     }
 
     SNMALLOC_FAST_PATH void remove(Ptr<T> item)
     {
-#ifndef NDEBUG
       debug_check_contains(item);
-#endif
 
       if (item->next != Terminator())
         item->next->prev = item->prev;
@@ -146,9 +139,7 @@ namespace snmalloc
       else
         head = item->next;
 
-#ifndef NDEBUG
       debug_check();
-#endif
     }
 
     void clear()
@@ -163,49 +154,56 @@ namespace snmalloc
 
     void debug_check_contains(Ptr<T> item)
     {
-#ifndef NDEBUG
-      debug_check();
-      Ptr<T> curr = head;
-
-      while (curr != item)
+      if constexpr (DEBUG)
       {
-        SNMALLOC_ASSERT(curr != Terminator());
-        curr = curr->next;
+        debug_check();
+        Ptr<T> curr = head;
+
+        while (curr != item)
+        {
+          SNMALLOC_ASSERT(curr != Terminator());
+          curr = curr->next;
+        }
+      }
+      else
+      {
+        UNUSED(item);
       }
-#else
-      UNUSED(item);
-#endif
     }
 
     void debug_check_not_contains(Ptr<T> item)
     {
-#ifndef NDEBUG
-      debug_check();
-      Ptr<T> curr = head;
-
-      while (curr != Terminator())
+      if constexpr (DEBUG)
       {
-        SNMALLOC_ASSERT(curr != item);
-        curr = curr->next;
+        debug_check();
+        Ptr<T> curr = head;
+
+        while (curr != Terminator())
+        {
+          SNMALLOC_ASSERT(curr != item);
+          curr = curr->next;
+        }
+      }
+      else
+      {
+        UNUSED(item);
       }
-#else
-      UNUSED(item);
-#endif
     }
 
     void debug_check()
     {
-#ifndef NDEBUG
-      Ptr<T> item = head;
-      Ptr<T> prev = Terminator();
-
-      while (item != Terminator())
+      if constexpr (DEBUG)
       {
-        SNMALLOC_ASSERT(item->prev == prev);
-        prev = item;
-        item = item->next;
+        Ptr<T> item = head;
+        Ptr<T> prev = Terminator();
+
+        while (item != Terminator())
+        {
+          SNMALLOC_ASSERT(item->prev == prev);
+          prev = item;
+          item = item->next;
+        }
       }
-#endif
     }
   };
 } // namespace snmalloc
diff --git a/src/mem/corealloc.h b/src/mem/corealloc.h
index 9a87d2f..66e6b7b 100644
--- a/src/mem/corealloc.h
+++ b/src/mem/corealloc.h
@@ -586,21 +586,22 @@ namespace snmalloc
       ChunkAllocator::register_local_state<SharedStateHandle>(
         get_backend_local_state(), chunk_local_state);
 
-#ifndef NDEBUG
-      for (smallsizeclass_t i = 0; i < NUM_SMALL_SIZECLASSES; i++)
+      if constexpr (DEBUG)
       {
-        size_t size = sizeclass_to_size(i);
-        smallsizeclass_t sc1 = size_to_sizeclass(size);
-        smallsizeclass_t sc2 = size_to_sizeclass_const(size);
-        size_t size1 = sizeclass_to_size(sc1);
-        size_t size2 = sizeclass_to_size(sc2);
+        for (smallsizeclass_t i = 0; i < NUM_SMALL_SIZECLASSES; i++)
+        {
+          size_t size = sizeclass_to_size(i);
+          smallsizeclass_t sc1 = size_to_sizeclass(size);
+          smallsizeclass_t sc2 = size_to_sizeclass_const(size);
+          size_t size1 = sizeclass_to_size(sc1);
+          size_t size2 = sizeclass_to_size(sc2);
 
-        SNMALLOC_ASSERT(sc1 == i);
-        SNMALLOC_ASSERT(sc1 == sc2);
-        SNMALLOC_ASSERT(size1 == size);
-        SNMALLOC_ASSERT(size1 == size2);
+          SNMALLOC_CHECK(sc1 == i);
+          SNMALLOC_CHECK(sc1 == sc2);
+          SNMALLOC_CHECK(size1 == size);
+          SNMALLOC_CHECK(size1 == size2);
+        }
       }
-#endif
     }
 
   public:
diff --git a/src/override/memcpy.cc b/src/override/memcpy.cc
index 6b51bc5..acfc6a6 100644
--- a/src/override/memcpy.cc
+++ b/src/override/memcpy.cc
@@ -30,11 +30,7 @@ namespace
 #ifdef SNMALLOC_CHECK_LOADS
     SNMALLOC_CHECK_LOADS
 #else
-#  ifdef NDEBUG
-    false
-#  else
-    true
-#  endif
+    DEBUG
 #endif
     ;
 
@@ -50,11 +46,7 @@ namespace
 #ifdef SNMALLOC_FAIL_FAST
     SNMALLOC_FAIL_FAST
 #else
-#  ifdef NDEBUG
-    true
-#  else
-    false
-#  endif
+    !DEBUG
 #endif
     ;
 
diff --git a/src/pal/pal_apple.h b/src/pal/pal_apple.h
index edf511b..69f4e5d 100644
--- a/src/pal/pal_apple.h
+++ b/src/pal/pal_apple.h
@@ -113,9 +113,8 @@ namespace snmalloc
     {
       SNMALLOC_ASSERT(is_aligned_block<page_size>(p, size));
 
-#  if !defined(NDEBUG)
-      memset(p, 0x5a, size);
-#  endif
+      if constexpr (DEBUG)
+        memset(p, 0x5a, size);
 
       // `MADV_FREE_REUSABLE` can only be applied to writable pages,
       // otherwise it's an error.
diff --git a/src/pal/pal_bsd.h b/src/pal/pal_bsd.h
index cf64244..a07b7c5 100644
--- a/src/pal/pal_bsd.h
+++ b/src/pal/pal_bsd.h
@@ -35,9 +35,9 @@ namespace snmalloc
     {
       SNMALLOC_ASSERT(is_aligned_block<OS::page_size>(p, size));
 
-#if !defined(NDEBUG)
-      memset(p, 0x5a, size);
-#endif
+      if constexpr (DEBUG)
+        memset(p, 0x5a, size);
+
       madvise(p, size, MADV_FREE);
 
       if constexpr (PalEnforceAccess)
diff --git a/src/pal/pal_linux.h b/src/pal/pal_linux.h
index 39d402d..139a6af 100644
--- a/src/pal/pal_linux.h
+++ b/src/pal/pal_linux.h
@@ -70,11 +70,11 @@ namespace snmalloc
 
       if constexpr (PalEnforceAccess)
       {
-#  if !defined(NDEBUG)
         // Fill memory so that when we switch the pages back on we don't make
         // assumptions on the content.
-        memset(p, 0x5a, size);
-#  endif
+        if constexpr (DEBUG)
+          memset(p, 0x5a, size);
+
         madvise(p, size, MADV_FREE);
         mprotect(p, size, PROT_NONE);
       }
diff --git a/src/pal/pal_posix.h b/src/pal/pal_posix.h
index bc05f9f..4689f69 100644
--- a/src/pal/pal_posix.h
+++ b/src/pal/pal_posix.h
@@ -189,11 +189,11 @@ namespace snmalloc
 
       if constexpr (PalEnforceAccess)
       {
-#if !defined(NDEBUG)
         // Fill memory so that when we switch the pages back on we don't make
         // assumptions on the content.
-        memset(p, 0x5a, size);
-#endif
+        if constexpr (DEBUG)
+          memset(p, 0x5a, size);
+
         mprotect(p, size, PROT_NONE);
       }
       else
diff --git a/src/test/perf/external_pointer/externalpointer.cc b/src/test/perf/external_pointer/externalpointer.cc
index e2fdb06..b589124 100644
--- a/src/test/perf/external_pointer/externalpointer.cc
+++ b/src/test/perf/external_pointer/externalpointer.cc
@@ -95,11 +95,8 @@ int main(int, char**)
   setup();
 
   xoroshiro::p128r64 r;
-#  ifdef NDEBUG
-  size_t nn = 30;
-#  else
-  size_t nn = 3;
-#  endif
+
+  size_t nn = snmalloc::DEBUG ? 30 : 3;
 
   for (size_t n = 0; n < nn; n++)
     test::test_external_pointer(r);