diff --git a/src/gba/gba-sio.c b/src/gba/gba-sio.c
index f179ba303..d598ffa2a 100644
--- a/src/gba/gba-sio.c
+++ b/src/gba/gba-sio.c
@@ -7,6 +7,13 @@
 
 #include "gba-io.h"
 
+const int GBASIOCyclesPerTransfer[4][MAX_GBAS] = {
+	{ 31457, 62914, 94371, 125829 },
+	{ 7864, 15728, 23592, 31457 },
+	{ 5242, 10485, 15728, 20971 },
+	{ 2621, 5242, 7864, 10485 }
+};
+
 static struct GBASIODriver* _lookupDriver(struct GBASIO* sio, enum GBASIOMode mode) {
 	switch (mode) {
 	case SIO_NORMAL_8:
diff --git a/src/gba/gba-sio.h b/src/gba/gba-sio.h
index 29de1738a..ebc2df7b3 100644
--- a/src/gba/gba-sio.h
+++ b/src/gba/gba-sio.h
@@ -8,6 +8,10 @@
 
 #include "util/common.h"
 
+#define MAX_GBAS 4
+
+extern const int GBASIOCyclesPerTransfer[4][MAX_GBAS];
+
 enum GBASIOMode {
 	SIO_NORMAL_8 = 0,
 	SIO_NORMAL_32 = 1,