diff --git a/include/rvl/OS/OSFastCast.h b/include/rvl/OS/OSFastCast.h
index 8db17517..8aa2e04a 100644
--- a/include/rvl/OS/OSFastCast.h
+++ b/include/rvl/OS/OSFastCast.h
@@ -71,11 +71,11 @@ static inline u8 __OSf32tou8(register f32 arg) {
 
     return r;
 }
-static inline void OSf32tou16(const f32 *in, u16 *out) {
+static inline void OSf32tou16(const f32 *in, volatile u16 *out) {
     *out = __OSf32tou16(*in);
 }
 
-static inline void OSf32tou8(const f32 *in, u8 *out) {
+static inline void OSf32tou8(const f32 *in, volatile u8 *out) {
     *out = __OSf32tou8(*in);
 }
 static inline f32 __OSs16tof32(register const s16 *arg) {
@@ -109,7 +109,7 @@ static inline s16 __OSf32tos16(register f32 arg) {
     return r;
 }
 
-static inline void OSf32tos16(const f32 *in, s16 *out) {
+static inline void OSf32tos16(const f32 *in, volatile s16 *out) {
     *out = __OSf32tos16(*in);
 }