diff --git a/src/emucore/CartMDM.cxx b/src/emucore/CartMDM.cxx
index 7eaca526e..e76526b47 100644
--- a/src/emucore/CartMDM.cxx
+++ b/src/emucore/CartMDM.cxx
@@ -21,7 +21,8 @@
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 CartridgeMDM::CartridgeMDM(const ByteBuffer& image, size_t size,
                            const string& md5, const Settings& settings)
-  : Cartridge(settings, md5)
+  : Cartridge(settings, md5),
+    mySize(size)
 {
   // Allocate array for the ROM image
   myImage = make_unique<uInt8[]>(mySize);
diff --git a/src/emucore/CartSB.cxx b/src/emucore/CartSB.cxx
index 4c582c91c..796ecfcdf 100644
--- a/src/emucore/CartSB.cxx
+++ b/src/emucore/CartSB.cxx
@@ -21,7 +21,8 @@
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 CartridgeSB::CartridgeSB(const ByteBuffer& image, size_t size,
                          const string& md5, const Settings& settings)
-  : Cartridge(settings, md5)
+  : Cartridge(settings, md5),
+    mySize(size)
 {
   // Allocate array for the ROM image
   myImage = make_unique<uInt8[]>(mySize);