diff --git a/src/ds/defines.h b/src/ds/defines.h
index e67e36d..a240739 100644
--- a/src/ds/defines.h
+++ b/src/ds/defines.h
@@ -20,6 +20,14 @@
 #  define SNMALLOC_COLD __attribute__((cold))
 #endif
 
+#if defined(__cpp_constinit) && __cpp_constinit >= 201907
+#  define SNMALLOC_CONSTINIT_FN constinit
+#  define SNMALLOC_CONSTINIT_STATIC constinit const
+#else
+#  define SNMALLOC_CONSTINIT_FN constexpr
+#  define SNMALLOC_CONSTINIT_STATIC constexpr
+#endif
+
 #if !defined(__clang__) && defined(__GNUC__)
 #  define GCC_NOT_CLANG
 #endif
diff --git a/src/pal/pal_bsd_aligned.h b/src/pal/pal_bsd_aligned.h
index c93eb4c..bac3e82 100644
--- a/src/pal/pal_bsd_aligned.h
+++ b/src/pal/pal_bsd_aligned.h
@@ -23,7 +23,7 @@ namespace snmalloc
     static constexpr uint64_t pal_features =
       AlignedAllocation | PALBSD<OS>::pal_features;
 
-    static constexpr size_t minimum_alloc_size = 4096;
+    static SNMALLOC_CONSTINIT_STATIC size_t minimum_alloc_size = 4096;
 
     /**
      * Reserve memory at a specific alignment.
diff --git a/src/pal/pal_windows.h b/src/pal/pal_windows.h
index 3c95525..847a04b 100644
--- a/src/pal/pal_windows.h
+++ b/src/pal/pal_windows.h
@@ -58,7 +58,7 @@ namespace snmalloc
 #  endif
       ;
 
-    static constexpr size_t minimum_alloc_size = 0x10000;
+    static SNMALLOC_CONSTINIT_STATIC size_t minimum_alloc_size = 0x10000;
 
     static constexpr size_t page_size = 0x1000;