diff --git a/src/pal/pal_bsd.h b/src/pal/pal_bsd.h
index a07b7c5..4689b43 100644
--- a/src/pal/pal_bsd.h
+++ b/src/pal/pal_bsd.h
@@ -10,8 +10,8 @@ namespace snmalloc
    * Generic *BSD PAL mixin.  This provides features that are common to the BSD
    * family.
    */
-  template<typename OS>
-  class PALBSD : public PALPOSIX<OS>
+  template<typename OS, auto... Args>
+  class PALBSD : public PALPOSIX<OS, Args...>
   {
   public:
     /**
diff --git a/src/pal/pal_bsd_aligned.h b/src/pal/pal_bsd_aligned.h
index c770a52..4c88287 100644
--- a/src/pal/pal_bsd_aligned.h
+++ b/src/pal/pal_bsd_aligned.h
@@ -10,8 +10,8 @@ namespace snmalloc
    * This adds aligned allocation using `MAP_ALIGNED` to the generic BSD
    * implementation.  This flag is supported by NetBSD and FreeBSD.
    */
-  template<class OS>
-  class PALBSD_Aligned : public PALBSD<OS>
+  template<class OS, auto... Args>
+  class PALBSD_Aligned : public PALBSD<OS, Args...>
   {
   public:
     /**
diff --git a/src/pal/pal_freebsd.h b/src/pal/pal_freebsd.h
index 916fc70..d24f4b7 100644
--- a/src/pal/pal_freebsd.h
+++ b/src/pal/pal_freebsd.h
@@ -13,6 +13,15 @@
 #    endif
 #  endif
 
+/**
+ * Direct system-call wrappers so that we can skip libthr interception, which
+ * won't work if malloc is broken.
+ * @{
+ */
+extern "C" ssize_t __sys_writev(int fd, const struct iovec* iov, int iovcnt);
+extern "C" int __sys_fsync(int fd);
+/// @}
+
 namespace snmalloc
 {
   /**
@@ -21,7 +30,8 @@ namespace snmalloc
    * This adds FreeBSD-specific aligned allocation to the generic BSD
    * implementation.
    */
-  class PALFreeBSD : public PALBSD_Aligned<PALFreeBSD>
+  class PALFreeBSD
+  : public PALBSD_Aligned<PALFreeBSD, __sys_writev, __sys_fsync>
   {
   public:
     /**
diff --git a/src/pal/pal_posix.h b/src/pal/pal_posix.h
index 16c5ef7..add7712 100644
--- a/src/pal/pal_posix.h
+++ b/src/pal/pal_posix.h
@@ -34,11 +34,13 @@ namespace snmalloc
    * efficient implementation.  Subclasses should provide more efficient
    * implementations using platform-specific functionality.
    *
-   * The template parameter for this is the subclass and is used for explicit
-   * up casts to allow this class to call non-virtual methods on the templated
-   * version.
+   * The first template parameter for this is the subclass and is used for
+   * explicit up casts to allow this class to call non-virtual methods on the
+   * templated version.  The next two allow subclasses to provide `writev` and
+   * `fsync` implementations that bypass any libc machinery that might not be
+   * working when an early-malloc error appears.
    */
-  template<class OS>
+  template<class OS, auto writev = ::writev, auto fsync = ::fsync>
   class PALPOSIX : public PalTimerDefaultImpl<PALPOSIX<OS>>
   {
     /**