diff --git a/src/gb/io.c b/src/gb/io.c
index 437e318c5..9cb6d221c 100644
--- a/src/gb/io.c
+++ b/src/gb/io.c
@@ -408,7 +408,7 @@ void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
 			case REG_BCPD:
 				GBVideoProcessDots(&gb->video);
 				GBVideoWritePalette(&gb->video, address, value);
-				break;
+				return;
 			case REG_OCPS:
 				gb->video.ocpIndex = value & 0x3F;
 				gb->video.ocpIncrement = value & 0x80;
@@ -417,7 +417,7 @@ void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
 			case REG_OCPD:
 				GBVideoProcessDots(&gb->video);
 				GBVideoWritePalette(&gb->video, address, value);
-				break;
+				return;
 			case REG_SVBK:
 				GBMemorySwitchWramBank(&gb->memory, value);
 				value = gb->memory.wramCurrentBank;
@@ -537,7 +537,9 @@ uint8_t GBIORead(struct GB* gb, unsigned address) {
 			case REG_HDMA3:
 			case REG_HDMA4:
 			case REG_HDMA5:
+			case REG_BCPS:
 			case REG_BCPD:
+			case REG_OCPS:
 			case REG_OCPD:
 			case REG_SVBK:
 				// Handled transparently by the registers
diff --git a/src/gb/video.c b/src/gb/video.c
index 47fa1c3c9..cc8301527 100644
--- a/src/gb/video.c
+++ b/src/gb/video.c
@@ -354,7 +354,9 @@ void GBVideoWritePalette(struct GBVideo* video, uint16_t address, uint8_t value)
 			if (video->bcpIncrement) {
 				++video->bcpIndex;
 				video->bcpIndex &= 0x3F;
-				video->p->memory.io[REG_BCPD] = video->palette[video->bcpIndex >> 1];
+				video->p->memory.io[REG_BCPS] &= 0x80;
+				video->p->memory.io[REG_BCPS] |= video->bcpIndex;
+				video->p->memory.io[REG_BCPD] = video->palette[video->bcpIndex >> 1] >> (8 * (video->bcpIndex & 1));
 			}
 			break;
 		case REG_OCPD:
@@ -369,7 +371,9 @@ void GBVideoWritePalette(struct GBVideo* video, uint16_t address, uint8_t value)
 			if (video->ocpIncrement) {
 				++video->ocpIndex;
 				video->ocpIndex &= 0x3F;
-				video->p->memory.io[REG_OCPD] = video->palette[8 * 4 + (video->ocpIndex >> 1)];
+				video->p->memory.io[REG_OCPS] &= 0x80;
+				video->p->memory.io[REG_OCPS] |= video->ocpIndex;
+				video->p->memory.io[REG_OCPD] = video->palette[8 * 4 + (video->ocpIndex >> 1)] >> (8 * (video->ocpIndex & 1));
 			}
 			break;
 		}