diff --git a/src/fds_apu.c b/src/fds_apu.c
index 8115c03..f57d480 100644
--- a/src/fds_apu.c
+++ b/src/fds_apu.c
@@ -282,13 +282,13 @@ void FDSSoundReset(void) {
 	GameExpSound.RChange = FDS_ESI;
 }
 
-DECLFR(FDSSoundRead) {
+uint8 FDSSoundRead(uint32 A) {
 	if (A >= 0x4040 && A < 0x4080) return FDSWaveRead(A);
 	if (A >= 0x4090 && A < 0x4093) return FDSSRead(A);
 	return X.DB;
 }
 
-DECLFW(FDSSoundWrite) {
+void FDSSoundWrite(uint32 A, uint8 V) {
 	if (A >= 0x4040 && A < 0x4080) FDSWaveWrite(A, V);
 	else if (A >= 0x4080 && A < 0x408B) FDSSWrite(A, V);
 }
diff --git a/src/fds_apu.h b/src/fds_apu.h
index 0aac02c..92902a3 100644
--- a/src/fds_apu.h
+++ b/src/fds_apu.h
@@ -1,12 +1,14 @@
 #ifndef FDS_APU_H
 #define FDS_APU_H
 
+#include "fceu-types.h"
+
 void FDSSoundReset(void);
 void FDSSoundStateAdd(void);
 
-/* Used for fds conversion-based mappers to allow access to fds apu registers */
+/* Used for FDS conversion-based mappers to allow access to FDS APU registers */
 void FDSSoundPower(void); 
-DECLFR(FDSSoundRead);   /* $4040-$407F, $4090-$4092 */
-DECLFW(FDSSoundWrite);  /* $4040-$407F, $4080-$408A */
+uint8 FDSSoundRead(uint32 A);          /* $4040-$407F, $4090-$4092 */
+void FDSSoundWrite(uint32 A, uint8 V); /* $4040-$407F, $4080-$408A */
 
-#endif /* FDS_APU_H */
\ No newline at end of file
+#endif /* FDS_APU_H */