diff --git a/src/boards/resettxrom.c b/src/boards/resettxrom.c
index 96b3cb4..1047283 100644
--- a/src/boards/resettxrom.c
+++ b/src/boards/resettxrom.c
@@ -32,31 +32,33 @@ static uint8 submapper;
 
 static void M313CW(uint32 A, uint8 V) {
 	/*FCEU_printf("CHR: A:%04x V:%02x 0:%02x\n", A, V, EXPREGS[0]);*/
+	uint32_t bank;
 	switch (submapper) {
-	case 0: V = (EXPREGS[0] << 7) | (V & 0x7F); break;
-	case 1: V = (EXPREGS[0] << 7) | (V & 0x7F); break;
-	case 2: V = (EXPREGS[0] << 8) | (V & 0xFF); break;
-	case 3: V = (EXPREGS[0] << 8) | (V & 0xFF); break;
-	case 4: V = (EXPREGS[0] << 7) | (V & 0x7F); break;
+	default: bank = (EXPREGS[0] << 7) | (V & 0x7F); break;
+	case 1: bank = (EXPREGS[0] << 7) | (V & 0x7F); break;
+	case 2: bank = (EXPREGS[0] << 8) | (V & 0xFF); break;
+	case 3: bank = (EXPREGS[0] << 8) | (V & 0xFF); break;
+	case 4: bank = (EXPREGS[0] << 7) | (V & 0x7F); break;
 	}
-	setchr1(A, V);
+	setchr1(A, bank);
 }
 
 static void M313PW(uint32 A, uint8 V) {
 	/*FCEU_printf("PRG: A:%04x V:%02x 0:%02x\n", A, V, EXPREGS[0]);*/
+	uint32_t bank;
 	switch (submapper) {
-	case 0: V = (EXPREGS[0] << 4) | (V & 0x0F); break;
-	case 1: V = (EXPREGS[0] << 5) | (V & 0x1F); break;
-	case 2: V = (EXPREGS[0] << 4) | (V & 0x0F); break;
-	case 3: V = (EXPREGS[0] << 5) | (V & 0x1F); break;
+	default: bank = (EXPREGS[0] << 4) | (V & 0x0F); break;
+	case 1: bank = (EXPREGS[0] << 5) | (V & 0x1F); break;
+	case 2: bank = (EXPREGS[0] << 4) | (V & 0x0F); break;
+	case 3: bank = (EXPREGS[0] << 5) | (V & 0x1F); break;
 	case 4:
 		if (EXPREGS[0] == 0)
-			V = (EXPREGS[0] << 5) | (V & 0x1F);
+			bank = (EXPREGS[0] << 5) | (V & 0x1F);
 		else
-			V = (EXPREGS[0] << 4) | (V & 0x0F);
+			bank = (EXPREGS[0] << 4) | (V & 0x0F);
 		break;
 	}
-	setprg8(A, V);
+	setprg8(A, bank);
 }
 
 static void M313Reset(void) {