diff --git a/libc/include/setjmp.h b/libc/include/setjmp.h
index d44946f..195f251 100644
--- a/libc/include/setjmp.h
+++ b/libc/include/setjmp.h
@@ -71,6 +71,8 @@
 int setjmp(jmp_buf __env);
 void longjmp(jmp_buf __env, int __value);
 
+#define setjmp(__env) setjmp(__env)
+
 int sigsetjmp(sigjmp_buf __env, int __save_signal_mask)
     __INTRODUCED_IN_ARM(9) __INTRODUCED_IN_MIPS(12) __INTRODUCED_IN_X86(12);
 void siglongjmp(sigjmp_buf __env, int __value)
diff --git a/tests/headers/posix/setjmp_h.c b/tests/headers/posix/setjmp_h.c
index b6b75ee..6544d2a 100644
--- a/tests/headers/posix/setjmp_h.c
+++ b/tests/headers/posix/setjmp_h.c
@@ -30,6 +30,12 @@
 
 #include "header_checks.h"
 
+// POSIX says it's undefined whether `setjmp` is a macro or a function,
+// but C11 says it's a macro, and the C standard always wins.
+#if !defined(setjmp)
+#error setjmp
+#endif
+
 static void setjmp_h() {
   TYPE(jmp_buf);
   TYPE(sigjmp_buf);