diff --git a/libc/generic/ansi/include/time.h b/libc/generic/ansi/include/time.h
index 33bc95b6..c25ea93a 100644
--- a/libc/generic/ansi/include/time.h
+++ b/libc/generic/ansi/include/time.h
@@ -70,6 +70,8 @@ size_t strftime(char *__restrict dest, size_t max_size,
 extern "C" {
 #endif
 
+int nanosleep(const struct timespec *, struct timespec *);
+
 int clock_getres(clockid_t, struct timespec *);
 int clock_gettime(clockid_t, struct timespec *);
 int clock_settime(clockid_t, const struct timespec *);
diff --git a/libc/generic/ansi/src/time-stubs.cpp b/libc/generic/ansi/src/time-stubs.cpp
index cc5fd747..0531ee89 100644
--- a/libc/generic/ansi/src/time-stubs.cpp
+++ b/libc/generic/ansi/src/time-stubs.cpp
@@ -45,6 +45,11 @@ size_t strftime(char *__restrict dest, size_t max_size,
 
 // POSIX extensions.
 
+int nanosleep(const struct timespec *, struct timespec *) {
+	__ensure(!"Not implemented");
+	__builtin_unreachable();
+}
+
 int clock_getres(clockid_t, struct timespec *) {
 	__ensure(!"Not implemented");
 	__builtin_unreachable();