diff --git a/drivers/mtd/tests/mtd_oobtest.c b/drivers/mtd/tests/mtd_oobtest.c
index 6bcff42..933f7e5 100644
--- a/drivers/mtd/tests/mtd_oobtest.c
+++ b/drivers/mtd/tests/mtd_oobtest.c
@@ -30,7 +30,7 @@
 
 #define PRINT_PREF KERN_INFO "mtd_oobtest: "
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -366,6 +366,13 @@
 
 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		printk(KERN_CRIT "CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
 	printk(PRINT_PREF "MTD device: %d\n", dev);
 
 	mtd = get_mtd_device(NULL, dev);
diff --git a/drivers/mtd/tests/mtd_pagetest.c b/drivers/mtd/tests/mtd_pagetest.c
index 186b14c..afafb69 100644
--- a/drivers/mtd/tests/mtd_pagetest.c
+++ b/drivers/mtd/tests/mtd_pagetest.c
@@ -30,7 +30,7 @@
 
 #define PRINT_PREF KERN_INFO "mtd_pagetest: "
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -504,6 +504,13 @@
 
 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		printk(KERN_CRIT "CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
 	printk(PRINT_PREF "MTD device: %d\n", dev);
 
 	mtd = get_mtd_device(NULL, dev);
diff --git a/drivers/mtd/tests/mtd_readtest.c b/drivers/mtd/tests/mtd_readtest.c
index 7560453..550fe51 100644
--- a/drivers/mtd/tests/mtd_readtest.c
+++ b/drivers/mtd/tests/mtd_readtest.c
@@ -29,7 +29,7 @@
 
 #define PRINT_PREF KERN_INFO "mtd_readtest: "
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -170,6 +170,12 @@
 
 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		return -EINVAL;
+	}
+
 	printk(PRINT_PREF "MTD device: %d\n", dev);
 
 	mtd = get_mtd_device(NULL, dev);
diff --git a/drivers/mtd/tests/mtd_speedtest.c b/drivers/mtd/tests/mtd_speedtest.c
index 79d53ee..493b367 100644
--- a/drivers/mtd/tests/mtd_speedtest.c
+++ b/drivers/mtd/tests/mtd_speedtest.c
@@ -29,7 +29,7 @@
 
 #define PRINT_PREF KERN_INFO "mtd_speedtest: "
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -361,6 +361,13 @@
 
 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		printk(KERN_CRIT "CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
 	if (count)
 		printk(PRINT_PREF "MTD device: %d    count: %d\n", dev, count);
 	else
diff --git a/drivers/mtd/tests/mtd_stresstest.c b/drivers/mtd/tests/mtd_stresstest.c
index 3c9008a..52ffd91 100644
--- a/drivers/mtd/tests/mtd_stresstest.c
+++ b/drivers/mtd/tests/mtd_stresstest.c
@@ -30,7 +30,7 @@
 
 #define PRINT_PREF KERN_INFO "mtd_stresstest: "
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -250,6 +250,13 @@
 
 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		printk(KERN_CRIT "CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
 	printk(PRINT_PREF "MTD device: %d\n", dev);
 
 	mtd = get_mtd_device(NULL, dev);
diff --git a/drivers/mtd/tests/mtd_subpagetest.c b/drivers/mtd/tests/mtd_subpagetest.c
index 2b51842..1a05bfa 100644
--- a/drivers/mtd/tests/mtd_subpagetest.c
+++ b/drivers/mtd/tests/mtd_subpagetest.c
@@ -29,7 +29,7 @@
 
 #define PRINT_PREF KERN_INFO "mtd_subpagetest: "
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -379,6 +379,13 @@
 
 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		printk(KERN_CRIT "CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
 	printk(PRINT_PREF "MTD device: %d\n", dev);
 
 	mtd = get_mtd_device(NULL, dev);
diff --git a/drivers/mtd/tests/mtd_torturetest.c b/drivers/mtd/tests/mtd_torturetest.c
index 25786ce..03ab649 100644
--- a/drivers/mtd/tests/mtd_torturetest.c
+++ b/drivers/mtd/tests/mtd_torturetest.c
@@ -46,7 +46,7 @@
 module_param(pgcnt, int, S_IRUGO);
 MODULE_PARM_DESC(pgcnt, "number of pages per eraseblock to torture (0 => all)");
 
-static int dev;
+static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 
@@ -213,6 +213,13 @@
 	printk(KERN_INFO "=================================================\n");
 	printk(PRINT_PREF "Warning: this program is trying to wear out your "
 	       "flash, stop it if this is not wanted.\n");
+
+	if (dev < 0) {
+		printk(PRINT_PREF "Please specify a valid mtd-device via module paramter\n");
+		printk(KERN_CRIT "CAREFUL: This test wipes all data on the specified MTD device!\n");
+		return -EINVAL;
+	}
+
 	printk(PRINT_PREF "MTD device: %d\n", dev);
 	printk(PRINT_PREF "torture %d eraseblocks (%d-%d) of mtd%d\n",
 	       ebcnt, eb, eb + ebcnt - 1, dev);