diff --git a/include/Kyoto/CMemoryCardSys.hpp b/include/Kyoto/CMemoryCardSys.hpp
index eac3961a..9dde62ee 100644
--- a/include/Kyoto/CMemoryCardSys.hpp
+++ b/include/Kyoto/CMemoryCardSys.hpp
@@ -26,8 +26,8 @@ struct FileHandle {
 
 struct ProbeResults {
   ECardResult x0_error;
-  uint x4_cardSize;   /* in megabits */
-  uint x8_sectorSize; /* in bytes */
+  int x4_cardSize;   /* in megabits */
+  int x8_sectorSize; /* in bytes */
 };
 
 class CMemoryCardSys {
diff --git a/src/MetroidPrime/CMemoryCardDriver.cpp b/src/MetroidPrime/CMemoryCardDriver.cpp
index 59b03757..03d9ce13 100644
--- a/src/MetroidPrime/CMemoryCardDriver.cpp
+++ b/src/MetroidPrime/CMemoryCardDriver.cpp
@@ -370,7 +370,46 @@ void CMemoryCardDriver::StartCardProbe() {
   UpdateCardProbe();
 }
 
-void CMemoryCardDriver::UpdateCardProbe() {}
+void CMemoryCardDriver::UpdateCardProbe() {
+  ProbeResults result = CMemoryCardSys::IsMemoryCardInserted(x0_cardPort);
+  ECardResult error = result.x0_error;
+
+  if (error == kCR_READY && result.x8_sectorSize != 0x2000) {
+    x10_state = kS_CardProbeFailed;
+    x14_error = kE_CardNon8KSectors;
+  } else if (error != kCR_BUSY) {
+    if (error == kCR_WRONGDEVICE) {
+      x10_state = kS_CardProbeFailed;
+      x14_error = kE_CardWrongDevice;
+    } else if (error != kCR_READY) {
+      NoCardFound();
+    } else {
+      x10_state = kS_CardProbeDone;
+      StartMountCard();
+    }
+  }
+
+  // switch (result.x0_error) {
+  // case kCR_READY:
+  //   if (result.x8_sectorSize != 0x2000) {
+  //     x10_state = kS_CardProbeFailed;
+  //     x14_error = kE_CardNon8KSectors;
+  //   } else {
+  //     x10_state = kS_CardProbeDone;
+  //     StartMountCard();
+  //   }
+  //   break;
+  // case kCR_BUSY:
+  //   break;
+  // case kCR_WRONGDEVICE:
+  //   x10_state = kS_CardProbeFailed;
+  //   x14_error = kE_CardWrongDevice;
+  //   break;
+  // default:
+  //   NoCardFound();
+  //   break;
+  // }
+}
 
 void CMemoryCardDriver::StartMountCard() {}