2 files changed, 9 insertions, 5 deletions
diff --git a/src/bfs.h b/src/bfs.h
index 70a7282..ab96bf5 100644
--- a/src/bfs.h
+++ b/src/bfs.h
@@ -59,11 +59,6 @@ extern const char bfs_ldlibs[];
 // Fundamental utilities
 
 /**
- * Get the length of an array.
- */
-#define countof(...) (sizeof(__VA_ARGS__) / sizeof(0[__VA_ARGS__]))
-
-/**
  * False sharing/destructive interference/largest cache line size.
  */
 #ifdef __GCC_DESTRUCTIVE_SIZE
diff --git a/src/prelude.h b/src/prelude.h
index 3b1c4e5..1663af6 100644
--- a/src/prelude.h
+++ b/src/prelude.h
@@ -88,6 +88,15 @@
 
 #endif // !C23
 
+// Future C standard backports
+
+/**
+ * Get the length of an array.
+ *
+ * https://www.open-std.org/JTC1/SC22/WG14/www/docs/n3469.htm
+ */
+#define countof(...) (sizeof(__VA_ARGS__) / sizeof(0[__VA_ARGS__]))
+
 // Feature detection
 
 // https://clang.llvm.org/docs/LanguageExtensions.html#has-attribute