diff --git a/libc/include/sys/ucontext.h b/libc/include/sys/ucontext.h
index 9060ab7..f150ac7 100644
--- a/libc/include/sys/ucontext.h
+++ b/libc/include/sys/ucontext.h
@@ -150,7 +150,8 @@
   stack_t uc_stack;
   mcontext_t uc_mcontext;
   sigset_t uc_sigmask;
-  /* TODO: __fpregs_mem? */
+  char __padding[128 - sizeof(sigset_t)];
+  struct _libc_fpstate __fpregs_mem;
 } ucontext_t;
 
 #elif defined(__mips__)
@@ -238,7 +239,31 @@
 typedef long greg_t;
 typedef greg_t gregset_t[NGREG];
 
-typedef struct user_fpregs_struct* fpregset_t;
+struct _libc_fpxreg {
+  unsigned short significand[4];
+  unsigned short exponent;
+  unsigned short padding[3];
+};
+
+struct _libc_xmmreg {
+  uint32_t element[4];
+};
+
+struct _libc_fpstate {
+  uint16_t cwd;
+  uint16_t swd;
+  uint16_t ftw;
+  uint16_t fop;
+  uint64_t rip;
+  uint64_t rdp;
+  uint32_t mxcsr;
+  uint32_t mxcr_mask;
+  struct _libc_fpxreg _st[8];
+  struct _libc_xmmreg _xmm[16];
+  uint32_t padding[24];
+};
+
+typedef struct _libc_fpstate* fpregset_t;
 
 typedef struct {
   gregset_t gregs;
@@ -252,7 +277,8 @@
   stack_t uc_stack;
   mcontext_t uc_mcontext;
   sigset_t uc_sigmask;
-  /* TODO: __fpregs_mem? */
+  char __padding[128 - sizeof(sigset_t)];
+  struct _libc_fpstate __fpregs_mem;
 } ucontext_t;
 
 #endif