diff --git a/libc/include/bits/signal_types.h b/libc/include/bits/signal_types.h
index 699e257..d98901c 100644
--- a/libc/include/bits/signal_types.h
+++ b/libc/include/bits/signal_types.h
@@ -28,18 +28,11 @@
 
 #pragma once
 
-#include <limits.h>
 #include <sys/cdefs.h>
-#include <sys/types.h>
 
-/* For 64-bit, the kernel's struct sigaction doesn't match the POSIX one,
- * so we need to expose our own and translate behind the scenes.
- * For 32-bit, we're stuck with the definitions we already shipped,
- * even though they contain a sigset_t that's too small. See sigaction64.
- */
-#define sigaction __kernel_sigaction
+#include <limits.h>
 #include <linux/signal.h>
-#undef sigaction
+#include <sys/types.h>
 
 /* The arm and x86 kernel header files don't define _NSIG. */
 #ifndef _KERNEL__NSIG
@@ -64,8 +57,13 @@
 typedef struct { unsigned long __bits[_KERNEL__NSIG/(8*sizeof(long))]; } sigset64_t;
 #endif
 
+/* The kernel's struct sigaction doesn't match the POSIX one. */
+
 #if defined(__LP64__)
 
+/* For 64-bit, that's the only problem, and we only need two structs
+ * for source compatibility with 32-bit. */
+
 #define __SIGACTION_BODY \
   int sa_flags; \
   union { \
@@ -82,6 +80,12 @@
 
 #else
 
+/* For 32-bit, Android's ABIs used a too-small sigset_t that doesn't
+ * support RT signals, so we need two different structs.
+ */
+
+/* The arm32 kernel headers also pollute the namespace with these,
+ * but our header scrubber doesn't know how to remove #defines. */
 #undef sa_handler
 #undef sa_sigaction
 
@@ -95,7 +99,6 @@
   void (*sa_restorer)(void);
 };
 
-/* This matches the kernel's internal structure. */
 struct sigaction64 {
   union {
     sighandler_t sa_handler;
diff --git a/libc/kernel/tools/defaults.py b/libc/kernel/tools/defaults.py
index ac12fc7..5340216 100644
--- a/libc/kernel/tools/defaults.py
+++ b/libc/kernel/tools/defaults.py
@@ -97,6 +97,9 @@
     # Remove unused macros (http://b/262917450).
     "__force": "",
     "__user": "",
+    # Rename the kernel's sigaction so we can expose our POSIX one publicly,
+    # but translate to the kernel's one internally.
+    "sigaction": "__kernel_sigaction",
     }
 
 
diff --git a/libc/kernel/uapi/asm-arm/asm/signal.h b/libc/kernel/uapi/asm-arm/asm/signal.h
index 838bb13..fde3b9e 100644
--- a/libc/kernel/uapi/asm-arm/asm/signal.h
+++ b/libc/kernel/uapi/asm-arm/asm/signal.h
@@ -52,7 +52,7 @@
 #define MINSIGSTKSZ 2048
 #define SIGSTKSZ 8192
 #include <asm-generic/signal-defs.h>
-struct sigaction {
+struct __kernel_sigaction {
   union {
     __sighandler_t _sa_handler;
     void(* _sa_sigaction) (int, struct siginfo *, void *);
diff --git a/libc/kernel/uapi/asm-generic/signal.h b/libc/kernel/uapi/asm-generic/signal.h
index bea99a7..21c7100 100644
--- a/libc/kernel/uapi/asm-generic/signal.h
+++ b/libc/kernel/uapi/asm-generic/signal.h
@@ -61,7 +61,7 @@
 #ifdef SA_RESTORER
 #define __ARCH_HAS_SA_RESTORER
 #endif
-struct sigaction {
+struct __kernel_sigaction {
   __sighandler_t sa_handler;
   unsigned long sa_flags;
 #ifdef SA_RESTORER
diff --git a/libc/kernel/uapi/asm-x86/asm/signal.h b/libc/kernel/uapi/asm-x86/asm/signal.h
index 2e51445..96ac8fb 100644
--- a/libc/kernel/uapi/asm-x86/asm/signal.h
+++ b/libc/kernel/uapi/asm-x86/asm/signal.h
@@ -56,7 +56,7 @@
 #include <asm-generic/signal-defs.h>
 #ifndef __ASSEMBLY__
 #ifdef __i386__
-struct sigaction {
+struct __kernel_sigaction {
   union {
     __sighandler_t _sa_handler;
     void(* _sa_sigaction) (int, struct siginfo *, void *);
@@ -68,7 +68,7 @@
 #define sa_handler _u._sa_handler
 #define sa_sigaction _u._sa_sigaction
 #else
-struct sigaction {
+struct __kernel_sigaction {
   __sighandler_t sa_handler;
   unsigned long sa_flags;
   __sigrestore_t sa_restorer;