diff --git a/pcsx2/SIO/Memcard/MemoryCardProtocol.cpp b/pcsx2/SIO/Memcard/MemoryCardProtocol.cpp
index 4c998ad3ad..4f7269ff7e 100644
--- a/pcsx2/SIO/Memcard/MemoryCardProtocol.cpp
+++ b/pcsx2/SIO/Memcard/MemoryCardProtocol.cpp
@@ -191,22 +191,27 @@ void MemoryCardProtocol::SetTerminator()
 {
 	MC_LOG.WriteLn("%s", __FUNCTION__);
 	PS1_FAIL();
-	const u8 newTerminator = g_Sio2FifoIn.front();
+	mcd->term = g_Sio2FifoIn.front();
 	g_Sio2FifoIn.pop_front();
-	const u8 oldTerminator = mcd->term;
-	mcd->term = newTerminator;
 	g_Sio2FifoOut.push_back(0x00);
 	g_Sio2FifoOut.push_back(0x2b);
-	g_Sio2FifoOut.push_back(oldTerminator);
+	g_Sio2FifoOut.push_back(mcd->term);
 }
 
+// This one is a bit unusual. Old and new versions of MCMAN seem to handle this differently.
+// Some commands may check [4] for the terminator. Others may check [3]. Typically, older
+// MCMAN revisions will exclusively check [4], and newer revisions will check both [3] and [4]
+// for different values. In all cases, they expect to see a valid terminator value.
+//
+// Also worth noting old revisions of MCMAN will not set anything other than 0x55 for the terminator,
+// while newer revisions will set the terminator to another value (most commonly 0x5a).
 void MemoryCardProtocol::GetTerminator()
 {
 	MC_LOG.WriteLn("%s", __FUNCTION__);
 	PS1_FAIL();
 	g_Sio2FifoOut.push_back(0x2b);
 	g_Sio2FifoOut.push_back(mcd->term);
-	g_Sio2FifoOut.push_back(static_cast<u8>(Terminator::DEFAULT));
+	g_Sio2FifoOut.push_back(mcd->term);
 }
 
 void MemoryCardProtocol::WriteData()
@@ -521,6 +526,7 @@ void MemoryCardProtocol::AuthF3()
 	}
 	else
 	{
+		mcd->term = Terminator::READY;
 		The2bTerminator(5);
 	}
 }
diff --git a/pcsx2/SIO/Sio.cpp b/pcsx2/SIO/Sio.cpp
index f0bd8ac2fe..5b28cc6e37 100644
--- a/pcsx2/SIO/Sio.cpp
+++ b/pcsx2/SIO/Sio.cpp
@@ -101,7 +101,7 @@ void AutoEject::Set(size_t port, size_t slot)
 	if (mcds[port][slot].autoEjectTicks == 0)
 	{
 		mcds[port][slot].autoEjectTicks = 60; // 60 frames is enough.
-		mcds[port][slot].term = 0x55; // Reset terminator to default (0x55), forces the PS2 to recheck the memcard.
+		mcds[port][slot].term = Terminator::NOT_READY; // Reset terminator to NOT_READY (0x66), forces the PS2 to recheck the memcard.
 	}
 }
 
diff --git a/pcsx2/SIO/Sio2.cpp b/pcsx2/SIO/Sio2.cpp
index f99c8e56cb..c9dcadc8cd 100644
--- a/pcsx2/SIO/Sio2.cpp
+++ b/pcsx2/SIO/Sio2.cpp
@@ -265,12 +265,12 @@ void Sio2::Memcard()
 	if (mcd->autoEjectTicks)
 	{
 		SetRecv1(Recv1::DISCONNECTED);
-		g_Sio2FifoOut.push_back(0x00); // Because Sio2::Write pops the first g_Sio2FifoIn member
+		g_Sio2FifoOut.push_back(0xff); // Because Sio2::Write pops the first g_Sio2FifoIn member
 
 		while (!g_Sio2FifoIn.empty())
 		{
 			g_Sio2FifoIn.pop_front();
-			g_Sio2FifoOut.push_back(0x00);
+			g_Sio2FifoOut.push_back(0xff);
 		}
 
 		return;
diff --git a/pcsx2/SIO/SioTypes.h b/pcsx2/SIO/SioTypes.h
index 2668a9fb54..42794de705 100644
--- a/pcsx2/SIO/SioTypes.h
+++ b/pcsx2/SIO/SioTypes.h
@@ -170,5 +170,6 @@ namespace Recv3
 
 namespace Terminator
 {
-	static constexpr u32 DEFAULT = 0x55;
+	static constexpr u32 NOT_READY = 0x66;
+	static constexpr u32 READY = 0x55;
 } // namespace Terminator