diff --git a/libc/include/sys/vfs.h b/libc/include/sys/vfs.h
index 6a55c99..6fce3b4 100644
--- a/libc/include/sys/vfs.h
+++ b/libc/include/sys/vfs.h
@@ -34,40 +34,51 @@
 
 __BEGIN_DECLS
 
-/* These correspond to the kernel's statfs64 type. */
+/* The kernel's __kernel_fsid_t has a 'val' member but glibc uses '__val'. */
+typedef struct { int __val[2]; } __fsid_t;
+
+/* Our struct statfs corresponds to the kernel's statfs64 type. */
 #ifdef __mips__
 struct statfs {
-    uint32_t        f_type;
-    uint32_t        f_bsize;
-    uint32_t        f_frsize;
-    uint32_t        __pad;
-    uint64_t        f_blocks;
-    uint64_t        f_bfree;
-    uint64_t        f_files;
-    uint64_t        f_ffree;
-    uint64_t        f_bavail;
-    __kernel_fsid_t f_fsid;
-    uint32_t        f_namelen;
-    uint32_t        f_flags;
-    uint32_t        f_spare[5];
+    uint32_t f_type;
+    uint32_t f_bsize;
+    uint32_t f_frsize;
+    uint32_t __pad;
+    uint64_t f_blocks;
+    uint64_t f_bfree;
+    uint64_t f_files;
+    uint64_t f_ffree;
+    uint64_t f_bavail;
+    __fsid_t f_fsid;
+    uint32_t f_namelen;
+    uint32_t f_flags;
+    uint32_t f_spare[5];
 };
 #else
 struct statfs {
-    uint32_t        f_type;
-    uint32_t        f_bsize;
-    uint64_t        f_blocks;
-    uint64_t        f_bfree;
-    uint64_t        f_bavail;
-    uint64_t        f_files;
-    uint64_t        f_ffree;
-    __kernel_fsid_t f_fsid;
-    uint32_t        f_namelen;
-    uint32_t        f_frsize;
-    uint32_t        f_flags;
-    uint32_t        f_spare[4];
+    uint32_t f_type;
+    uint32_t f_bsize;
+    uint64_t f_blocks;
+    uint64_t f_bfree;
+    uint64_t f_bavail;
+    uint64_t f_files;
+    uint64_t f_ffree;
+    __fsid_t f_fsid;
+    uint32_t f_namelen;
+    uint32_t f_frsize;
+    uint32_t f_flags;
+    uint32_t f_spare[4];
 };
 #endif
 
+/* Source compatibility with glibc. */
+#define statfs64 statfs
+
+/* Declare that we have the f_namelen, f_frsize, and f_flags fields. */
+#define _STATFS_F_NAMELEN
+#define _STATFS_F_FRSIZE
+#define _STATFS_F_FLAGS
+
 #define  ADFS_SUPER_MAGIC      0xadf5
 #define  AFFS_SUPER_MAGIC      0xADFF
 #define  BEFS_SUPER_MAGIC      0x42465331
@@ -113,8 +124,8 @@
 #define  XFS_SUPER_MAGIC       0x58465342
 #define  _XIAFS_SUPER_MAGIC    0x012FD16D
 
-extern int statfs(const char *, struct statfs *);
-extern int fstatfs(int, struct statfs *);
+extern int statfs(const char*, struct statfs*) __nonnull((1, 2));
+extern int fstatfs(int, struct statfs*) __nonnull((2));
 
 __END_DECLS