diff --git a/testing/cmd_1.c b/testing/cmd_1.c
index f3861be..84e2fd4 100644
--- a/testing/cmd_1.c
+++ b/testing/cmd_1.c
@@ -112,6 +112,8 @@ int test_cmd_read_fast_1chan(void)
 	int ret;
 	unsigned int flags = comedi_get_subdevice_flags(device,subdevice);
 
+	/* attempt to make subdevice the current 'read' subdevice */
+	if(flags&SDF_CMD_READ) comedi_set_read_subdevice(device,subdevice);
 	if(!(flags&SDF_CMD) || (comedi_get_read_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;
@@ -172,6 +174,8 @@ int test_cmd_write_fast_1chan(void)
 	{
 		num_bytes = num_samples * sizeof(sampl_t);
 	}
+	/* attempt to make subdevice the current 'write' subdevice */
+	if(flags&SDF_CMD_WRITE) comedi_set_write_subdevice(device,subdevice);
 	if(!(flags&SDF_CMD) || (comedi_get_write_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;
diff --git a/testing/cmd_2.c b/testing/cmd_2.c
index 20fa906..bd6cabc 100644
--- a/testing/cmd_2.c
+++ b/testing/cmd_2.c
@@ -21,6 +21,8 @@ int test_cmd_fifo_depth_check(void)
 	int len;
 	unsigned int flags = comedi_get_subdevice_flags(device,subdevice);
 
+	/* attempt to make subdevice the current 'read' subdevice */
+	if(flags&SDF_CMD_READ) comedi_set_read_subdevice(device,subdevice);
 	if(!(flags&SDF_CMD) || (comedi_get_read_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;
diff --git a/testing/cmd_3.c b/testing/cmd_3.c
index 4b0ae74..73030ef 100644
--- a/testing/cmd_3.c
+++ b/testing/cmd_3.c
@@ -19,8 +19,11 @@ static int do_continuous(int multiplier);
 int test_cmd_continuous(void)
 {
 	int mult;
+	unsigned int flags = comedi_get_subdevice_flags(device,subdevice);
 
-	if(!(comedi_get_subdevice_flags(device,subdevice)&SDF_CMD)){
+	/* attempt to make subdevice the current 'read' subdevice */
+	if(flags&SDF_CMD_READ) comedi_set_read_subdevice(device,subdevice);
+	if(!(flags&SDF_CMD) || (comedi_get_read_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;
 	}
diff --git a/testing/inttrig.c b/testing/inttrig.c
index 7188b89..f4dcf5a 100644
--- a/testing/inttrig.c
+++ b/testing/inttrig.c
@@ -25,6 +25,8 @@ int test_cmd_start_inttrig(void)
 	unsigned int flags;
 
 	flags = comedi_get_subdevice_flags(device,subdevice);
+	/* attempt to make subdevice the current 'read' subdevice */
+	if(flags&SDF_CMD_READ) comedi_set_read_subdevice(device,subdevice);
 	if(!(flags&SDF_CMD) || (comedi_get_read_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;
diff --git a/testing/mmap.c b/testing/mmap.c
index 0f9efd2..b7d0a56 100644
--- a/testing/mmap.c
+++ b/testing/mmap.c
@@ -68,6 +68,8 @@ int test_mmap(void)
 
 	flags = comedi_get_subdevice_flags(device,subdevice);
 
+	/* attempt to make subdevice the current 'read' subdevice */
+	if(flags&SDF_CMD_READ) comedi_set_read_subdevice(device,subdevice);
 	if(!(flags&SDF_CMD) || (comedi_get_read_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;
diff --git a/testing/select.c b/testing/select.c
index 9ec5ed1..46790fa 100644
--- a/testing/select.c
+++ b/testing/select.c
@@ -30,6 +30,8 @@ int test_read_select(void)
 	unsigned int flags;
 
 	flags = comedi_get_subdevice_flags(device,subdevice);
+	/* attempt to make subdevice the current 'read' subdevice */
+	if(flags&SDF_CMD_READ) comedi_set_read_subdevice(device,subdevice);
 	if(!(flags&SDF_CMD) || (comedi_get_read_subdevice(device)!=subdevice)){
 		printf("not applicable\n");
 		return 0;