diff --git a/src/dos/dos_programs.cpp b/src/dos/dos_programs.cpp
index 38cda889..3b202c26 100644
--- a/src/dos/dos_programs.cpp
+++ b/src/dos/dos_programs.cpp
@@ -59,6 +59,37 @@ Bitu DEBUG_EnableDebugger(void);
 void MSCDEX_SetCDInterface(int intNr, int forceCD);
 static Bitu ZDRIVE_NUM = 25;
 
+static const char* UnmountHelper(char umount) {
+	int i_drive;
+	if (umount < '0' || umount > 3+'0')
+		i_drive = toupper(umount) - 'A';
+	else
+		i_drive = umount - '0';
+
+	if (i_drive >= DOS_DRIVES || i_drive < 0 || (Drives[i_drive] == NULL && imageDiskList[i_drive] == NULL))
+		return MSG_Get("PROGRAM_MOUNT_UMOUNT_NOT_MOUNTED");
+
+	if (Drives[i_drive]) {
+		switch (DriveManager::UnmountDrive(i_drive)) {
+			case 1: return MSG_Get("PROGRAM_MOUNT_UMOUNT_NO_VIRTUAL");
+			case 2: return MSG_Get("MSCDEX_ERROR_MULTIPLE_CDROMS");
+		}
+		Drives[i_drive] = 0;
+		mem_writeb(Real2Phys(dos.tables.mediaid)+i_drive*9,0);
+		if (i_drive == DOS_GetDefaultDrive()) {
+			DOS_SetDrive(ZDRIVE_NUM);
+		}
+
+	}
+
+	if (imageDiskList[i_drive]) {
+		delete imageDiskList[i_drive];
+		imageDiskList[i_drive] = NULL;
+	}
+
+	return MSG_Get("PROGRAM_MOUNT_UMOUNT_SUCCESS");
+}
+
 class MOUNT : public Program {
 public:
 	void ListMounts(void) {
@@ -120,27 +151,7 @@ public:
 
 		/* Check for unmounting */
 		if (cmd->FindString("-u",umount,false)) {
-			umount[0] = toupper(umount[0]);
-			int i_drive = umount[0]-'A';
-				if (i_drive < DOS_DRIVES && i_drive >= 0 && Drives[i_drive]) {
-					switch (DriveManager::UnmountDrive(i_drive)) {
-					case 0:
-						Drives[i_drive] = 0;
-						mem_writeb(Real2Phys(dos.tables.mediaid)+i_drive*9,0);
-						if(i_drive == DOS_GetDefaultDrive()) 
-							DOS_SetDrive(ZDRIVE_NUM);
-						WriteOut(MSG_Get("PROGRAM_MOUNT_UMOUNT_SUCCESS"),umount[0]);
-						break;
-					case 1:
-						WriteOut(MSG_Get("PROGRAM_MOUNT_UMOUNT_NO_VIRTUAL"));
-						break;
-					case 2:
-						WriteOut(MSG_Get("MSCDEX_ERROR_MULTIPLE_CDROMS"));
-						break;
-					}
-				} else {
-					WriteOut(MSG_Get("PROGRAM_MOUNT_UMOUNT_NOT_MOUNTED"),umount[0]);
-				}
+			WriteOut(UnmountHelper(umount[0]), toupper(umount[0]));
 			return;
 		}
 		
@@ -1150,26 +1161,7 @@ public:
 		std::string umount;
 		/* Check for unmounting */
 		if (cmd->FindString("-u",umount,false)) {
-			umount[0] = toupper(umount[0]);
-			int i_drive = umount[0]-'A';
-				if (i_drive < DOS_DRIVES && i_drive >= 0 && Drives[i_drive]) {
-					switch (DriveManager::UnmountDrive(i_drive)) {
-					case 0:
-						Drives[i_drive] = 0;
-						if (i_drive == DOS_GetDefaultDrive()) 
-							DOS_SetDrive(toupper('Z') - 'A');
-						WriteOut(MSG_Get("PROGRAM_MOUNT_UMOUNT_SUCCESS"),umount[0]);
-						break;
-					case 1:
-						WriteOut(MSG_Get("PROGRAM_MOUNT_UMOUNT_NO_VIRTUAL"));
-						break;
-					case 2:
-						WriteOut(MSG_Get("MSCDEX_ERROR_MULTIPLE_CDROMS"));
-						break;
-					}
-				} else {
-					WriteOut(MSG_Get("PROGRAM_MOUNT_UMOUNT_NOT_MOUNTED"),umount[0]);
-				}
+			WriteOut(UnmountHelper(umount[0]), toupper(umount[0]));
 			return;
 		}