diff --git a/src/eez/modules/dib-dcp405/dib-dcp405.h b/src/eez/modules/dib-dcp405/dib-dcp405.h
index a4bdf4d01..593327bfe 100644
--- a/src/eez/modules/dib-dcp405/dib-dcp405.h
+++ b/src/eez/modules/dib-dcp405/dib-dcp405.h
@@ -25,6 +25,7 @@ static const uint16_t MODULE_REVISION_DCP405_R2B5  = 0x0205;
 static const uint16_t MODULE_REVISION_DCP405_R2B7  = 0x0207;
 static const uint16_t MODULE_REVISION_DCP405_R2B11 = 0x020B;
 static const uint16_t MODULE_REVISION_DCP405_R3B1  = 0x0301;
+static const uint16_t MODULE_REVISION_DCP405_R3B3  = 0x0303;
 
 namespace eez {
 namespace dcp405 {
diff --git a/src/eez/modules/dib-dcp405/ioexp.cpp b/src/eez/modules/dib-dcp405/ioexp.cpp
index 4bd7ff620..840aa372e 100644
--- a/src/eez/modules/dib-dcp405/ioexp.cpp
+++ b/src/eez/modules/dib-dcp405/ioexp.cpp
@@ -124,7 +124,7 @@ uint8_t IOExpander::getRegValue(int i) {
     } else if (reg == REG_GPIOA) {
         value = REG_VALUE_GPIOA;
     } else if (reg == REG_GPIOB) {
-		if (slot.moduleRevision >= MODULE_REVISION_DCP405_R3B1) {
+		if (slot.moduleRevision >= MODULE_REVISION_DCP405_R3B1 && slot.moduleRevision < MODULE_REVISION_DCP405_R3B3) {
 			value = R3B1_REG_VALUE_GPIOB;
 		} else {
 			value = REG_VALUE_GPIOB;
@@ -322,7 +322,7 @@ bool IOExpander::testBit(int io_bit) {
     auto result = (gpio & (1 << io_bit)) ? true : false;
 
     auto &slot = *g_slots[slotIndex];
-	if (slot.moduleRevision >= MODULE_REVISION_DCP405_R3B1) {
+	if (slot.moduleRevision >= MODULE_REVISION_DCP405_R3B1 && slot.moduleRevision < MODULE_REVISION_DCP405_R3B3) {
 		if (io_bit == IO_BIT_OUT_OVP_ENABLE) {
 			result = !result;
 		}
@@ -352,7 +352,7 @@ void IOExpander::changeBit(int io_bit, bool set) {
     }
 #endif
 
-	if (slot.moduleRevision >= MODULE_REVISION_DCP405_R3B1) {
+	if (slot.moduleRevision >= MODULE_REVISION_DCP405_R3B1 && slot.moduleRevision < MODULE_REVISION_DCP405_R3B3) {
 		if (io_bit == IO_BIT_OUT_OVP_ENABLE) {
 			set = !set;
 		}