diff --git a/app/app.c b/app/app.c
index 50f0b79..fba4689 100644
--- a/app/app.c
+++ b/app/app.c
@@ -1435,7 +1435,7 @@ void FUN_000075b0(void)
 	g_20000464 = 0;
 }
 
-void APP_ChangeStepDirectionMaybe(bool bFlag, uint8_t Direction)
+void APP_ChangeStepDirectionMaybe(bool bFlag, int8_t Direction)
 {
 	RADIO_ConfigureTX();
 	g_20000410 = gInfoCHAN_A->CHANNEL_SAVE;
diff --git a/app/main.c b/app/main.c
index 682fd85..b04a7a9 100644
--- a/app/main.c
+++ b/app/main.c
@@ -10,7 +10,7 @@
 extern void APP_SwitchToFM(void);
 extern void FUN_0000773c(void);
 extern void APP_SetFrequencyByStep(VFO_Info_t *pInfo, int8_t Step);
-extern void APP_ChangeStepDirectionMaybe(bool bFlag, uint8_t Direction);
+extern void APP_ChangeStepDirectionMaybe(bool bFlag, int8_t Direction);
 extern void APP_CycleOutputPower(void);
 extern void APP_FlipVoxSwitch(void);
 
diff --git a/app/menu.c b/app/menu.c
index 902b43f..4d06399 100644
--- a/app/menu.c
+++ b/app/menu.c
@@ -72,7 +72,7 @@ static const VOICE_ID_t MenuVoices[] = {
 	VOICE_ID_INVALID,
 };
 
-static void FUN_000074f8(uint8_t Direction)
+static void FUN_000074f8(int8_t Direction)
 {
 	g_20000381 = 1;
 	gMenuScrollDirection = Direction;
@@ -988,7 +988,7 @@ void MENU_Key_STAR(bool bKeyPressed, bool bKeyHeld)
 		if (gInfoCHAN_A->CHANNEL_SAVE < 207 && !gInfoCHAN_A->IsAM) {
 			if (gMenuCursor == MENU_R_CTCS || gMenuCursor == MENU_R_DCS) {
 				if (g_20000381 == 0) {
-					FUN_000074f8(0x01);
+					FUN_000074f8(1);
 					gRequestDisplayScreen = DISPLAY_MENU;
 					AUDIO_SetVoiceID(0,VOICE_ID_SCANNING_BEGIN);
 					AUDIO_PlaySingleVoice(1);
diff --git a/frequencies.c b/frequencies.c
index 513b924..0b1296e 100644
--- a/frequencies.c
+++ b/frequencies.c
@@ -113,12 +113,12 @@ uint32_t FREQUENCY_CalculateOutputPower(uint8_t TxpLow, uint8_t TxpMid, uint8_t
 	return TxpMid + ((TxpHigh - TxpMid) * (Frequency - Middle)) / (UpperLimit - Middle);
 }
 
-uint32_t FREQUENCY_FloorToStep(uint32_t Frequency, uint32_t Step, uint32_t Base)
+uint32_t FREQUENCY_FloorToStep(uint32_t Upper, int32_t Step, uint32_t Lower)
 {
 	uint32_t Index;
 
-	Index = (Frequency - Base) / Step;
-	return Base + (Step * Index);
+	Index = (Upper - Lower) / Step;
+	return Lower + (Step * Index);
 }
 
 int FREQUENCY_Check(VFO_Info_t *pInfo)
diff --git a/frequencies.h b/frequencies.h
index 73b57f0..1a91ae5 100644
--- a/frequencies.h
+++ b/frequencies.h
@@ -40,7 +40,7 @@ extern const uint16_t StepFrequencyTable[6];
 
 FREQUENCY_Band_t FREQUENCY_GetBand(uint32_t Frequency);
 uint32_t FREQUENCY_CalculateOutputPower(uint8_t TxpLow, uint8_t TxpMid, uint8_t TxpHigh, uint32_t LowerLimit, uint32_t Middle, uint32_t UpperLimit, uint32_t Frequency);
-uint32_t FREQUENCY_FloorToStep(uint32_t Frequency, uint32_t Step, uint32_t Base);
+uint32_t FREQUENCY_FloorToStep(uint32_t Upper, int32_t Step, uint32_t Lower);
 int FREQUENCY_Check(VFO_Info_t *pInfo);
 
 #endif
diff --git a/gui.c b/gui.c
index c684c84..f71904e 100644
--- a/gui.c
+++ b/gui.c
@@ -170,7 +170,7 @@ static const char gSubMenu_F_LOCK[6][4] = {
 
 GUI_DisplayType_t gScreenToDisplay;
 bool gIsInSubMenu;
-volatile uint8_t gStepDirection;
+volatile int8_t gStepDirection;
 GUI_DisplayType_t gRequestDisplayScreen;
 uint8_t g_200003BA;
 uint8_t g_200003BB;
@@ -181,7 +181,7 @@ bool gAskToSave;
 bool gAskToDelete;
 
 uint8_t gMenuCursor;
-uint8_t gMenuScrollDirection;
+int8_t gMenuScrollDirection;
 uint32_t gSubMenuSelection;
 
 void GUI_DisplayBatteryLevel(uint8_t BatteryLevel)
diff --git a/gui.h b/gui.h
index 48bbeac..8e5369a 100644
--- a/gui.h
+++ b/gui.h
@@ -93,7 +93,7 @@ enum {
 
 extern GUI_DisplayType_t gScreenToDisplay;
 extern bool gIsInSubMenu;
-extern volatile uint8_t gStepDirection;
+extern volatile int8_t gStepDirection;
 extern GUI_DisplayType_t gRequestDisplayScreen;
 extern uint8_t g_200003BA;
 extern uint8_t g_200003BB;
@@ -104,7 +104,7 @@ extern bool gAskToSave;
 extern bool gAskToDelete;
 
 extern uint8_t gMenuCursor;
-extern uint8_t gMenuScrollDirection;
+extern int8_t gMenuScrollDirection;
 extern uint32_t gSubMenuSelection;
 
 void GUI_DisplayBatteryLevel(uint8_t BatteryLevel);
diff --git a/radio.c b/radio.c
index ae68d20..38c6b1f 100644
--- a/radio.c
+++ b/radio.c
@@ -81,7 +81,7 @@ bool RADIO_CheckValidChannel(uint8_t Channel, bool bCheckScanList, uint8_t VFO)
 	return true;
 }
 
-uint8_t RADIO_FindNextChannel(uint8_t Channel, uint8_t Direction, bool bCheckScanList, uint8_t VFO)
+uint8_t RADIO_FindNextChannel(uint8_t Channel, int8_t Direction, bool bCheckScanList, uint8_t VFO)
 {
 	uint8_t i;
 
diff --git a/radio.h b/radio.h
index eaa1f48..3a71833 100644
--- a/radio.h
+++ b/radio.h
@@ -93,7 +93,7 @@ extern DCS_CodeType_t gCopyOfCodeType;
 extern uint8_t gCode;
 
 bool RADIO_CheckValidChannel(uint8_t ChNum, bool bCheckScanList, uint8_t RadioNum);
-uint8_t RADIO_FindNextChannel(uint8_t ChNum, uint8_t Direction, bool bCheckScanList, uint8_t RadioNum);
+uint8_t RADIO_FindNextChannel(uint8_t ChNum, int8_t Direction, bool bCheckScanList, uint8_t RadioNum);
 void RADIO_InitInfo(VFO_Info_t *pInfo, uint8_t ChannelSave, uint8_t ChIndex, uint32_t Frequency);
 void RADIO_ConfigureChannel(uint8_t RadioNum, uint32_t Arg);
 void RADIO_ConfigureSquelchAndOutputPower(VFO_Info_t *pInfo);