diff --git a/include/kabufuda/Card.hpp b/include/kabufuda/Card.hpp
index 12afea6..ad9ef59 100644
--- a/include/kabufuda/Card.hpp
+++ b/include/kabufuda/Card.hpp
@@ -524,6 +524,11 @@ public:
      */
     void close();
 
+    /**
+     * @brief Access host filename of card
+     */
+    const SystemString& cardFilename() const { return m_filename; }
+
     /**
      * @brief Gets card-scope error state
      * @return READY, BROKEN, or NOCARD
diff --git a/lib/kabufuda/Card.cpp b/lib/kabufuda/Card.cpp
index 780168c..a151f91 100644
--- a/lib/kabufuda/Card.cpp
+++ b/lib/kabufuda/Card.cpp
@@ -117,7 +117,7 @@ Card::Card(const SystemString& filename, const char* game, const char* maker) :
 
         /* Close and reopen in read/write mode */
         fclose(m_fileHandle);
-        m_fileHandle = Fopen(m_filename.c_str(), _S("r+"));
+        m_fileHandle = Fopen(m_filename.c_str(), _S("r+b"));
         rewind(m_fileHandle);
     }
 }
@@ -949,7 +949,7 @@ void Card::format(ECardSlot id, ECardSize size, EEncoding encoding)
         memset(data.get(), 0xFF, dataLen);
         fwrite(data.get(), 1, dataLen, m_fileHandle);
         fclose(m_fileHandle);
-        m_fileHandle = Fopen(m_filename.c_str(), _S("r+"));
+        m_fileHandle = Fopen(m_filename.c_str(), _S("r+b"));
     }
 }