diff --git a/rpcs3/Emu/Cell/Modules/cellGcmSys.cpp b/rpcs3/Emu/Cell/Modules/cellGcmSys.cpp
index 658b0bd654..9374112e68 100644
--- a/rpcs3/Emu/Cell/Modules/cellGcmSys.cpp
+++ b/rpcs3/Emu/Cell/Modules/cellGcmSys.cpp
@@ -82,7 +82,7 @@ u32 gcmIoOffsetToAddress(u32 ioOffset)
 {
 	const u32 upper12Bits = g_fxo->get<gcm_config>()->offsetTable.eaAddress[ioOffset >> 20];
 
-	if (static_cast<s16>(upper12Bits) < 0)
+	if (upper12Bits > 0xBFF)
 	{
 		return 0;
 	}
@@ -1035,7 +1035,7 @@ error_code cellGcmMapMainMemory(u32 ea, u32 size, vm::ptr<u32> offset)
 	// Use the offset table to find the next free io address
 	for (u32 io = 0, end = (rsx::get_current_renderer()->main_mem_size - cfg->reserved_size) >> 20, unmap_count = 1; io < end; unmap_count++)
 	{
-		if (static_cast<s16>(cfg->offsetTable.eaAddress[io + unmap_count - 1]) < 0)
+		if (cfg->offsetTable.eaAddress[io + unmap_count - 1] > 0xBFF)
 		{
 			if (unmap_count >= (size >> 20))
 			{
@@ -1088,17 +1088,13 @@ error_code cellGcmUnmapEaIoAddress(u32 ea)
 	const auto cfg = g_fxo->get<gcm_config>();
 	std::lock_guard lock(cfg->gcmio_mutex);
 
-	if (const u32 size = cfg->IoMapTable[ea >> 20])
+	if (u32 size = cfg->IoMapTable[ea >>= 20], io = cfg->offsetTable.ioAddress[ea]; size && io <= 0xBFF)
 	{
-		u32 io = cfg->offsetTable.ioAddress[ea];
-
-		if (auto error = sys_rsx_context_iounmap(0x55555555, io, size))
+		if (auto error = sys_rsx_context_iounmap(0x55555555, io << 20, size << 20))
 		{
 			return error;
 		}
 
-		ea >>= 20, io >>= 20;
-
 		const auto render = rsx::get_current_renderer();
 
 		for (u32 i = 0; i < size; i++)
@@ -1123,7 +1119,7 @@ error_code cellGcmUnmapIoAddress(u32 io)
 
 	if (u32 ea = cfg->offsetTable.eaAddress[io >>= 20], size = cfg->IoMapTable[ea]; size)
 	{
-		if (auto error = sys_rsx_context_iounmap(0x55555555, io, size))
+		if (auto error = sys_rsx_context_iounmap(0x55555555, io, size << 20))
 		{
 			return error;
 		}
@@ -1135,6 +1131,7 @@ error_code cellGcmUnmapIoAddress(u32 io)
 			cfg->offsetTable.eaAddress[io + i] = 0xFFFF;
 		}
 
+		cfg->IoMapTable[ea] = 0;
 		return CELL_OK;
 	}