diff --git a/configure.ac b/configure.ac
index f70579d..c1e469f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,22 +40,6 @@ AC_PROG_CPP
 AC_PROG_INSTALL
 AC_PROG_MAKE_SET
 
-# -- Checks for platform-specific features --
-
-AC_MSG_CHECKING([if null pointers have an all-zero representation])
-AC_RUN_IFELSE([
-    AC_LANG_PROGRAM([[#include <string.h>]],
-                    [[void *ptr = NULL; char buf[sizeof(ptr)] = { 0 };
-                      if (0 != memcmp(buf, &ptr, sizeof(ptr))) return 1;]])
-], [
-    AC_MSG_RESULT([yes])
-], [
-    AC_MSG_RESULT([no])
-    AC_MSG_ERROR(m4_normalize([
-        Null pointers do not have an all-zero representation on this platform.
-    ]))
-])
-
 # -- Checks for features --
 
 BOOKMARKFS_FEAT([bookmarkfs-util], [no], [the BookmarkFS utility library])
diff --git a/src/hashmap.c b/src/hashmap.c
index a1cd827..6a1106c 100644
--- a/src/hashmap.c
+++ b/src/hashmap.c
@@ -300,17 +300,19 @@ hashmap_create (
     hashmap_hash_func *entry_hash
 ) {
     size_t buckets_len = BUCKET_CNT(EXP_MIN);
-    // XXX: Null pointers have an implementation-defined value
-    // per ISO C standard, and should not be zero-initialized with calloc().
-    // However, it is guaranteed to be zero on most, if not all,
-    // modern ABI standards that we know of.
+    // XXX: According to the ISO C standard, null pointers have an
+    // implementation-defined value, and should not be zero-initialized
+    // with calloc() or memset().
     //
-    // Nevertheless, we add a build-time check just in case (see configure.ac).
+    // However, it is guaranteed to be all-bits-zero on most,
+    // if not all, modern ABI standards that we know of.
+    // POSIX also has such requirements since POSIX.1-2024.
     //
     // See:
     // - <https://github.com/ARM-software/abi-aa>
     // - <https://github.com/riscv-non-isa/riscv-elf-psabi-doc>
     // - <https://gitlab.com/x86-psABIs/x86-64-ABI>
+    // - <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/stddef.h.html>
     struct bucket *buckets = xcalloc(buckets_len, sizeof(struct bucket));
 
     struct hashmap *h = xmalloc(sizeof(*h));