diff --git a/firmware/common/dir.c b/firmware/common/dir.c
index 4b4a5fa65d..aa55aeb9e9 100644
--- a/firmware/common/dir.c
+++ b/firmware/common/dir.c
@@ -67,6 +67,26 @@ static int strip_volume(const char* name, char* namecopy)
 #endif /* #ifdef HAVE_MULTIVOLUME */
 
 
+#ifdef HAVE_HOTSWAP
+// release all dir handles on a given volume "by force", to avoid leaks
+int release_dirs(int volume)
+{
+    DIR* pdir = opendirs;
+    int dd;
+    int closed = 0;
+    for ( dd=0; dd<MAX_OPEN_DIRS; dd++, pdir++)
+    {
+        if (pdir->fatdir.file.volume == volume)
+        {
+            pdir->busy = false; /* mark as available, no further action */
+            closed++;
+        }
+    }
+    return closed; /* return how many we did */
+}
+#endif /* #ifdef HAVE_HOTSWAP */
+
+
 DIR* opendir(const char* name)
 {
     char namecopy[MAX_PATH];
@@ -154,6 +174,10 @@ struct dirent* readdir(DIR* dir)
 {
     struct fat_direntry entry;
     struct dirent* theent = &(dir->theent);
+
+    if (!dir->busy)
+        return NULL;
+
 #ifdef HAVE_MULTIVOLUME
     /* Volumes (secondary file systems) get inserted into the root directory
         of the first volume, since we have no separate top level. */
diff --git a/firmware/common/disk.c b/firmware/common/disk.c
index 923dffbe46..fd6de55ddb 100644
--- a/firmware/common/disk.c
+++ b/firmware/common/disk.c
@@ -23,6 +23,8 @@
 #ifdef HAVE_MMC
 #include "ata_mmc.h"
 #endif
+#include "file.h" /* for release_dirs() */
+#include "dir.h" /* for release_files() */
 #include "disk.h"
 
 /* Partition table entry layout:
@@ -44,6 +46,7 @@
      ((long)array[pos+2] << 16 ) | ((long)array[pos+3] << 24 ))
 
 static struct partinfo part[8]; /* space for 4 partitions on 2 drives */
+static int vol_drive[NUM_VOLUMES]; /* mounted to which drive (-1 if none) */
 
 struct partinfo* disk_init(IF_MV_NONVOID(int drive))
 {
@@ -95,46 +98,86 @@ struct partinfo* disk_partinfo(int partition)
 
 int disk_mount_all(void)
 {
-    struct partinfo* pinfo;
-    int i,j;
-    int mounted = 0;
-    bool found;
-    int drives = 1;
+    int mounted;
+    int i;
+
+    fat_init(); /* reset all mounted partitions */
+    for (i=0; i<NUM_VOLUMES; i++)
+        vol_drive[i] = -1; /* mark all as unassigned */
+
+    mounted = disk_mount(0);
 #ifdef HAVE_MMC
     if (mmc_detect()) /* for Ondio, only if card detected */
     {
-        drives = 2; /* in such case we have two drives to try */
+        mounted += disk_mount(1); /* try 2nd "drive", too */
     }
 #endif
 
-    fat_init(); /* reset all mounted partitions */
-    for (j=0; j<drives; j++)
-    {
-        found = false; /* reset partition-on-drive flag */
-        pinfo = disk_init(IF_MV(j));
-        if (pinfo == NULL)
-        {
-            continue;
-        }
-        for (i=0; mounted<NUM_VOLUMES && i<4; i++)
-        {
-            if (!fat_mount(IF_MV2(mounted,) IF_MV2(j,) pinfo[i].start))
-            {
-                mounted++;
-                found = true; /* at least one valid entry */
-            }
-        }
-
-        if (!found && mounted<NUM_VOLUMES) /* none of the 4 entries worked? */
-        {   /* try "superfloppy" mode */
-            DEBUGF("No partition found, trying to mount sector 0.\n");
-            if (!fat_mount(IF_MV2(mounted,) IF_MV2(j,) 0))
-            {
-                mounted++;
-            }
-        }
-    }
-
     return mounted;
 }
 
+static int get_free_volume(void)
+{
+    int i;
+    for (i=0; i<NUM_VOLUMES; i++)
+    {
+        if (vol_drive[i] == -1) /* unassigned? */
+            return i;
+    }
+
+    return -1; /* none found */
+}
+
+int disk_mount(int drive)
+{
+    int i;
+    int mounted = 0; /* reset partition-on-drive flag */
+    int volume = get_free_volume();
+    struct partinfo* pinfo = disk_init(IF_MV(drive));
+
+    if (pinfo == NULL)
+    {
+        return 0;
+    }
+    for (i=0; volume != -1 && i<4; i++)
+    {
+        if (!fat_mount(IF_MV2(volume,) IF_MV2(drive,) pinfo[i].start))
+        {
+            mounted++;
+            vol_drive[volume] = drive; /* remember the drive for this volume */
+            volume = get_free_volume(); /* prepare next entry */
+        }
+    }
+
+    if (mounted == 0 && volume != -1) /* none of the 4 entries worked? */
+    {   /* try "superfloppy" mode */
+        DEBUGF("No partition found, trying to mount sector 0.\n");
+        if (!fat_mount(IF_MV2(volume,) IF_MV2(drive,) 0))
+        {
+            mounted = 1;
+            vol_drive[volume] = drive; /* remember the drive for this volume */
+        }
+    }
+    return mounted;
+}
+
+#ifdef HAVE_HOTSWAP
+int disk_unmount(int drive)
+{
+    int unmounted = 0;
+    int i;
+    for (i=0; i<NUM_VOLUMES; i++)
+    {
+        if (vol_drive[i] == drive)
+        {   /* force releasing resources */
+            vol_drive[i] = -1; /* mark unused */
+            unmounted++;
+            release_files(i);
+            release_dirs(i);
+            fat_unmount(i, false);
+        }
+    }
+
+    return unmounted;
+}
+#endif /* #ifdef HAVE_HOTSWAP */
diff --git a/firmware/common/file.c b/firmware/common/file.c
index f04f787b45..795fc7df7e 100644
--- a/firmware/common/file.c
+++ b/firmware/common/file.c
@@ -660,3 +660,23 @@ off_t filesize(int fd)
     
     return file->size;
 }
+
+
+#ifdef HAVE_HOTSWAP
+// release all file handles on a given volume "by force", to avoid leaks
+int release_files(int volume)
+{
+    struct filedesc* pfile = openfiles;
+    int fd;
+    int closed = 0;
+    for ( fd=0; fd<MAX_OPEN_FILES; fd++, pfile++)
+    {
+        if (pfile->fatfile.volume == volume)
+        {
+            pfile->busy = false; /* mark as available, no further action */
+            closed++;
+        }
+    }
+    return closed; /* return how many we did */
+}
+#endif /* #ifdef HAVE_HOTSWAP */
diff --git a/firmware/drivers/fat.c b/firmware/drivers/fat.c
index 3adca5e864..78aebd2e2b 100644
--- a/firmware/drivers/fat.c
+++ b/firmware/drivers/fat.c
@@ -482,7 +482,7 @@ int fat_mount(IF_MV2(int volume,) IF_MV2(int drive,) long startsector)
     return 0;
 }
 
-#ifdef HAVE_MULTIVOLUME
+#ifdef HAVE_HOTSWAP
 int fat_unmount(int volume, bool flush)
 {
     int rc;
@@ -511,7 +511,7 @@ int fat_unmount(int volume, bool flush)
     fat_bpb->mounted = false;
     return rc;
 }
-#endif
+#endif /* #ifdef HAVE_HOTSWAP */
 
 void fat_recalc_free(IF_MV_NONVOID(int volume))
 {
diff --git a/firmware/export/disk.h b/firmware/export/disk.h
index e8525d1f75..e10fe9e7dc 100644
--- a/firmware/export/disk.h
+++ b/firmware/export/disk.h
@@ -35,5 +35,7 @@ struct partinfo {
 struct partinfo* disk_init(IF_MV_NONVOID(int volume));
 struct partinfo* disk_partinfo(int partition);
 int disk_mount_all(void); /* returns the # of successful mounts */
+int disk_mount(int drive);
+int disk_unmount(int drive);
 
 #endif
diff --git a/firmware/include/dir.h b/firmware/include/dir.h
index 5c157e4696..8dcbb8e900 100644
--- a/firmware/include/dir.h
+++ b/firmware/include/dir.h
@@ -84,6 +84,8 @@ extern int rmdir(const char* name);
 
 extern struct dirent* readdir(DIR* dir);
 
+extern int release_dirs(int volume);
+
 #endif /* DIRFUNCTIONS_DEFINED */
 
 #endif
diff --git a/firmware/include/file.h b/firmware/include/file.h
index e76abaaa96..387c34cdd8 100644
--- a/firmware/include/file.h
+++ b/firmware/include/file.h
@@ -87,6 +87,7 @@ extern int remove(const char* pathname);
 extern int rename(const char* path, const char* newname);
 extern int ftruncate(int fd, off_t length);
 extern off_t filesize(int fd);
+extern int release_files(int volume);
 #endif /* SIMULATOR */
 
 #endif