diff --git a/libc/private/bionic_constants.h b/libc/private/bionic_constants.h
index 05914f4..6274fe2 100644
--- a/libc/private/bionic_constants.h
+++ b/libc/private/bionic_constants.h
@@ -16,7 +16,7 @@
 
 #pragma once
 
-#define NS_PER_S 1000000000
+#define NS_PER_S 1'000'000'000LL
 
 // Size of the shadow call stack. This can be small because these stacks only
 // contain return addresses. This must be a power of 2 so the mask trick works.
diff --git a/libc/private/bionic_time_conversions.h b/libc/private/bionic_time_conversions.h
index fb049f2..c6b3c78 100644
--- a/libc/private/bionic_time_conversions.h
+++ b/libc/private/bionic_time_conversions.h
@@ -45,6 +45,9 @@
 __LIBC_HIDDEN__ void monotonic_time_from_realtime_time(timespec& monotonic_time,
                                                        const timespec& realtime_time);
 
+__LIBC_HIDDEN__ void realtime_time_from_monotonic_time(timespec& realtime_time,
+                                                       const timespec& monotonic_time);
+
 __END_DECLS
 
 static inline int check_timespec(const timespec* ts, bool null_allowed) {