diff --git a/platform-independent/c/cli/src/mpw-cli.c b/platform-independent/c/cli/src/mpw-cli.c
index 20ed58a7..d379cff3 100644
--- a/platform-independent/c/cli/src/mpw-cli.c
+++ b/platform-independent/c/cli/src/mpw-cli.c
@@ -185,6 +185,7 @@ void cli_save(Arguments *args, Operation *operation);
 
 MPMasterKeyProvider cli_masterKeyProvider_op(Operation *operation);
 MPMasterKeyProvider cli_masterKeyProvider_str(const char *masterPassword);
+void cli_masterKeyProvider_free();
 
 /** ========================================================================
  *  MAIN                                                                     */
@@ -274,6 +275,7 @@ void cli_free(Arguments *args, Operation *operation) {
         mpw_marshal_free( &operation->user );
         operation->site = NULL;
         operation->question = NULL;
+        cli_masterKeyProvider_free();
     }
 }
 
@@ -457,22 +459,30 @@ void cli_user(Arguments *args, Operation *operation) {
 
     // Find mpsites file from parameters.
     FILE *sitesFile = NULL;
-    mpw_free_string( &operation->sitesPath );
-    operation->sitesPath = mpw_path( operation->fullName, mpw_marshal_format_extension( operation->sitesFormat ) );
-    if (!operation->sitesPath || !(sitesFile = fopen( operation->sitesPath, "r" ))) {
-        dbg( "Couldn't open configuration file:\n  %s: %s", operation->sitesPath, strerror( errno ) );
+    const char **extensions = NULL;
+    int count = mpw_marshal_format_extensions( operation->sitesFormat, &extensions );
+    for (int e = 0; !sitesFile && e < count; ++e) {
+        mpw_free_string( &operation->sitesPath );
+        operation->sitesPath = mpw_path( operation->fullName, extensions[e] );
 
-        // Try to fall back to the flat format.
-        if (!operation->sitesFormatFixed) {
-            mpw_free_string( &operation->sitesPath );
-            operation->sitesPath = mpw_path( operation->fullName, mpw_marshal_format_extension( MPMarshalFormatFlat ) );
-            if (operation->sitesPath && (sitesFile = fopen( operation->sitesPath, "r" )))
-                operation->sitesFormat = MPMarshalFormatFlat;
-            else
-                dbg( "Couldn't open configuration file:\n  %s: %s", operation->sitesPath, strerror( errno ) );
-        }
+        if (!operation->sitesPath || !(sitesFile = fopen( operation->sitesPath, "r" )))
+            dbg( "Couldn't open configuration file:\n  %s: %s", operation->sitesPath, strerror( errno ) );
     }
 
+    if (!sitesFile && !operation->sitesFormatFixed)
+        for (MPMarshalFormat format = MPMarshalFormatFirst; !sitesFile && format <= MPMarshalFormatLast; ++format) {
+            count = mpw_marshal_format_extensions( operation->sitesFormat, &extensions );
+
+            for (int e = 0; !sitesFile && e < count; ++e) {
+                mpw_free_string( &operation->sitesPath );
+                operation->sitesPath = mpw_path( operation->fullName, extensions[e] );
+
+                if (!operation->sitesPath || !(sitesFile = fopen( operation->sitesPath, "r" )))
+                    dbg( "Couldn't open configuration file:\n  %s: %s", operation->sitesPath, strerror( errno ) );
+            }
+        }
+    free( extensions );
+
     // Load the user object from mpsites.
     if (!sitesFile)
         mpw_free_string( &operation->sitesPath );
@@ -490,7 +500,8 @@ void cli_user(Arguments *args, Operation *operation) {
         MPMarshalError marshalError = { .type = MPMarshalSuccess };
         mpw_marshal_info_free( &sitesInputInfo );
         mpw_marshal_free( &operation->user );
-        operation->user = mpw_marshal_read( sitesInputData, sitesInputFormat, cli_masterKeyProvider_op( operation ), &marshalError );
+        operation->user = mpw_marshal_read( sitesInputData, sitesInputFormat,
+                cli_masterKeyProvider_op( operation ), &marshalError );
         if (marshalError.type == MPMarshalErrorMasterPassword && operation->allowPasswordUpdate) {
             // Update master password in mpsites.
             while (marshalError.type == MPMarshalErrorMasterPassword) {
@@ -498,14 +509,16 @@ void cli_user(Arguments *args, Operation *operation) {
                 inf( "To update the configuration with this new master password, first confirm the old master password." );
 
                 const char *importMasterPassword = NULL;
-                while (!importMasterPassword || !strlen( importMasterPassword ))
+                while (!importMasterPassword || !strlen( importMasterPassword )) {
+                    mpw_free_string( &importMasterPassword );
                     importMasterPassword = mpw_getpass( "Old master password: " );
+                }
 
                 mpw_marshal_free( &operation->user );
-                operation->user = mpw_marshal_read( sitesInputData, sitesInputFormat, cli_masterKeyProvider_str( importMasterPassword ), &marshalError );
-                mpw_free_string( &importMasterPassword );
-                
+                operation->user = mpw_marshal_read( sitesInputData, sitesInputFormat,
+                        cli_masterKeyProvider_str( importMasterPassword ), &marshalError );
                 operation->user->masterKeyProvider = cli_masterKeyProvider_op( operation );
+                mpw_free_string( &importMasterPassword );
             }
         }
         mpw_free_string( &sitesInputData );
@@ -772,15 +785,17 @@ void cli_mpw(Arguments *args, Operation *operation) {
 
 void cli_save(Arguments *args, Operation *operation) {
 
-    if (operation->sitesFormat == MPMarshalFormatNone)
-        return;
-
     if (!operation->sitesFormatFixed)
         operation->sitesFormat = MPMarshalFormatDefault;
 
+    const char **extensions = NULL;
+    if (!mpw_marshal_format_extensions( operation->sitesFormat, &extensions ))
+        return;
+
     mpw_free_string( &operation->sitesPath );
-    operation->sitesPath = mpw_path( operation->user->fullName, mpw_marshal_format_extension( operation->sitesFormat ) );
-    dbg( "Updating: %s (%s)", operation->sitesPath, mpw_nameForFormat( operation->sitesFormat ) );
+    operation->sitesPath = mpw_path( operation->user->fullName, extensions[0] );
+    dbg( "Updating: %s (%s)", operation->sitesPath, mpw_format_name( operation->sitesFormat ) );
+    free( extensions );
 
     FILE *sitesFile = NULL;
     if (!operation->sitesPath || !mpw_mkdirs( operation->sitesPath ) || !(sitesFile = fopen( operation->sitesPath, "w" ))) {
@@ -800,31 +815,48 @@ void cli_save(Arguments *args, Operation *operation) {
     fclose( sitesFile );
 }
 
-static MPMasterKey __cli_masterKeyProvider_currentKey;
-static MPAlgorithmVersion __cli_masterKeyProvider_currentAlgorithm;
-static const char *__cli_masterKeyProvider_currentPassword;
-static Operation *__cli_masterKeyProvider_currentOperation;
+static MPMasterKey __cli_masterKeyProvider_currentKey = NULL;
+static MPAlgorithmVersion __cli_masterKeyProvider_currentAlgorithm = (MPAlgorithmVersion)-1;
+static const char *__cli_masterKeyProvider_currentPassword = NULL;
+static Operation *__cli_masterKeyProvider_currentOperation = NULL;
+
 static MPMasterKey __cli_masterKeyProvider_op(MPAlgorithmVersion algorithm, const char *fullName) {
-    if (mpw_update_masterKey(&__cli_masterKeyProvider_currentKey, &__cli_masterKeyProvider_currentAlgorithm,
-                             algorithm, fullName, __cli_masterKeyProvider_currentOperation->masterPassword))
-        return __cli_masterKeyProvider_currentKey;
-    
+
+    if (mpw_update_master_key( &__cli_masterKeyProvider_currentKey, &__cli_masterKeyProvider_currentAlgorithm,
+            algorithm, fullName, __cli_masterKeyProvider_currentOperation->masterPassword ))
+        return mpw_memdup( __cli_masterKeyProvider_currentKey, MPMasterKeySize );
+
     return NULL;
 }
+
 static MPMasterKey __cli_masterKeyProvider_str(MPAlgorithmVersion algorithm, const char *fullName) {
-    if (mpw_update_masterKey(&__cli_masterKeyProvider_currentKey, &__cli_masterKeyProvider_currentAlgorithm,
-                             algorithm, fullName, __cli_masterKeyProvider_currentPassword))
-        return __cli_masterKeyProvider_currentKey;
-    
+
+    if (mpw_update_master_key( &__cli_masterKeyProvider_currentKey, &__cli_masterKeyProvider_currentAlgorithm,
+            algorithm, fullName, __cli_masterKeyProvider_currentPassword ))
+        return mpw_memdup( __cli_masterKeyProvider_currentKey, MPMasterKeySize );
+
     return NULL;
 }
 
 MPMasterKeyProvider cli_masterKeyProvider_op(Operation *operation) {
+
+    mpw_free_string( &__cli_masterKeyProvider_currentPassword );
     __cli_masterKeyProvider_currentOperation = operation;
     return __cli_masterKeyProvider_op;
 }
 
 MPMasterKeyProvider cli_masterKeyProvider_str(const char *masterPassword) {
-    __cli_masterKeyProvider_currentPassword = masterPassword;
+
+    mpw_free_string( &__cli_masterKeyProvider_currentPassword );
+    __cli_masterKeyProvider_currentPassword = mpw_strdup( masterPassword );
     return __cli_masterKeyProvider_str;
 }
+
+void cli_masterKeyProvider_free() {
+
+    mpw_free( &__cli_masterKeyProvider_currentKey, MPMasterKeySize );
+    __cli_masterKeyProvider_currentAlgorithm = (MPAlgorithmVersion)-1;
+    mpw_free_string( &__cli_masterKeyProvider_currentPassword );
+    __cli_masterKeyProvider_currentOperation = NULL;
+
+}
diff --git a/platform-independent/c/core/src/mpw-marshal.c b/platform-independent/c/core/src/mpw-marshal.c
index 5fe9bdd6..743204cd 100644
--- a/platform-independent/c/core/src/mpw-marshal.c
+++ b/platform-independent/c/core/src/mpw-marshal.c
@@ -181,7 +181,7 @@ static bool mpw_marshal_write_flat(
         if (!user->redacted) {
             // Clear Text
             mpw_free( &masterKey, MPMasterKeySize );
-            if (!(masterKey = user->masterKeyProvider( user->algorithm, user->fullName ))) {
+            if (!(masterKey = user->masterKeyProvider( site->algorithm, user->fullName ))) {
                 *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
                 return false;
             }
@@ -212,6 +212,7 @@ static bool mpw_marshal_write_flat(
 }
 
 #if MPW_JSON
+
 static bool mpw_marshal_write_json(
         char **out, const MPMarshalledUser *user, MPMarshalError *error) {
 
@@ -263,7 +264,7 @@ static bool mpw_marshal_write_json(
         if (!user->redacted) {
             // Clear Text
             mpw_free( &masterKey, MPMasterKeySize );
-            if (!(masterKey = user->masterKeyProvider( user->algorithm, user->fullName ))) {
+            if (!(masterKey = user->masterKeyProvider( site->algorithm, user->fullName ))) {
                 *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
                 return false;
             }
@@ -339,6 +340,7 @@ static bool mpw_marshal_write_json(
     *error = (MPMarshalError){ .type = MPMarshalSuccess };
     return true;
 }
+
 #endif
 
 bool mpw_marshal_write(
@@ -593,7 +595,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
             if (!user->redacted) {
                 // Clear Text
                 mpw_free( &masterKey, MPMasterKeySize );
-                if (!(masterKey = masterKeyProvider( user->algorithm, user->fullName ))) {
+                if (!(masterKey = masterKeyProvider( site->algorithm, user->fullName ))) {
                     *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
                     return NULL;
                 }
@@ -632,6 +634,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
 }
 
 #if MPW_JSON
+
 static void mpw_marshal_read_json_info(
         const char *in, MPMarshalInfo *info) {
 
@@ -713,7 +716,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         *error = (MPMarshalError){ MPMarshalErrorMissing, "Missing value for full name." };
         return NULL;
     }
-    if (!(masterKey = masterKeyProvider( user->algorithm, user->fullName ))) {
+    if (!(masterKey = masterKeyProvider( algorithm, fullName ))) {
         *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
         return NULL;
     }
@@ -779,7 +782,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (!user->redacted) {
             // Clear Text
             mpw_free( &masterKey, MPMasterKeySize );
-            if (!(masterKey = masterKeyProvider( user->algorithm, user->fullName ))) {
+            if (!(masterKey = masterKeyProvider( site->algorithm, user->fullName ))) {
                 *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
                 return NULL;
             }
@@ -827,6 +830,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
     *error = (MPMarshalError){ .type = MPMarshalSuccess };
     return user;
 }
+
 #endif
 
 MPMarshalInfo *mpw_marshal_read_info(
@@ -913,10 +917,41 @@ const char *mpw_marshal_format_extension(
         case MPMarshalFormatFlat:
             return "mpsites";
         case MPMarshalFormatJSON:
-            return "mpsites.json";
+            return "mpjson";
         default: {
             dbg( "Unknown format: %d", format );
             return NULL;
         }
     }
 }
+
+int mpw_marshal_format_extensions(
+        const MPMarshalFormat format, const char ***extensions) {
+
+    int count = 0;
+    switch (format) {
+        case MPMarshalFormatNone: {
+            break;
+        }
+        case MPMarshalFormatFlat: {
+            const char *array[3] = { mpw_marshal_format_extension( format ), "mpsites.txt", "txt" };
+            count = sizeof( array ) / sizeof( *array );
+            *extensions = realloc( *extensions, count * sizeof( const char * ) );
+            memcpy( *extensions, array, count * sizeof( const char * ) );
+            break;
+        }
+        case MPMarshalFormatJSON: {
+            const char *array[3] = { mpw_marshal_format_extension( format ), "mpsites.json", "json" };
+            count = sizeof( array ) / sizeof( *array );
+            *extensions = realloc( *extensions, sizeof( array ) );
+            memcpy( *extensions, array, sizeof( array ) );
+            break;
+        }
+        default: {
+            dbg( "Unknown format: %d", format );
+            break;
+        }
+    }
+
+    return count;
+}
diff --git a/platform-independent/c/core/src/mpw-marshal.h b/platform-independent/c/core/src/mpw-marshal.h
index 6d4210a2..f4f3a45e 100644
--- a/platform-independent/c/core/src/mpw-marshal.h
+++ b/platform-independent/c/core/src/mpw-marshal.h
@@ -38,6 +38,8 @@ typedef mpw_enum( unsigned int, MPMarshalFormat ) {
 #else
     MPMarshalFormatDefault = MPMarshalFormatFlat,
 #endif
+    MPMarshalFormatFirst = MPMarshalFormatFlat,
+    MPMarshalFormatLast = MPMarshalFormatJSON,
 };
 
 typedef mpw_enum( unsigned int, MPMarshalErrorType ) {
@@ -162,5 +164,12 @@ const char *mpw_nameForFormat(
  */
 const char *mpw_marshal_format_extension(
         const MPMarshalFormat format);
+/**
+ * @param extensions An array of filename extensions that are used for files of this format,
+ *        the first being the currently preferred/output extension.  Free after use.
+ * @return The amount of filename extensions returned in the array.
+ */
+int mpw_marshal_format_extensions(
+        const MPMarshalFormat format, const char ***extensions);
 
 #endif // _MPW_MARSHAL_H
diff --git a/platform-independent/c/core/src/mpw-util.c b/platform-independent/c/core/src/mpw-util.c
index 55cbf05a..8164d87f 100644
--- a/platform-independent/c/core/src/mpw-util.c
+++ b/platform-independent/c/core/src/mpw-util.c
@@ -490,17 +490,25 @@ const size_t mpw_utf8_strlen(const char *utf8String) {
     return charlen;
 }
 
+void *mpw_memdup(const void *src, size_t len) {
+
+    if (!src)
+        return NULL;
+
+    char *dst = malloc( len );
+    if (dst)
+        memcpy( dst, src, len );
+
+    return dst;
+}
+
 char *mpw_strdup(const char *src) {
 
     if (!src)
         return NULL;
 
     size_t len = strlen( src );
-    char *dst = malloc( len + 1 );
-    memcpy( dst, src, len );
-    dst[len] = '\0';
-
-    return dst;
+    return mpw_memdup( src, len + 1 );
 }
 
 char *mpw_strndup(const char *src, size_t max) {
diff --git a/platform-independent/c/core/src/mpw-util.h b/platform-independent/c/core/src/mpw-util.h
index 8765a9ef..38adac95 100644
--- a/platform-independent/c/core/src/mpw-util.h
+++ b/platform-independent/c/core/src/mpw-util.h
@@ -223,6 +223,8 @@ bool mpw_id_buf_equals(const char *id1, const char *id2);
 
 /** @return The amount of display characters in the given UTF-8 string. */
 const size_t mpw_utf8_strlen(const char *utf8String);
+/** Drop-in for memdup(3). */
+void *mpw_memdup(const void *src, size_t len);
 /** Drop-in for POSIX strdup(3). */
 char *mpw_strdup(const char *src);
 /** Drop-in for POSIX strndup(3). */