diff --git a/include/minix/optset.h b/include/minix/optset.h
index a7e088122..bd12b6ba4 100644
--- a/include/minix/optset.h
+++ b/include/minix/optset.h
@@ -4,6 +4,7 @@
 typedef enum {
   OPT_BOOL,
   OPT_STRING,
+  OPT_64INT,
   OPT_INT
 } optset_type;
 
diff --git a/lib/libsys/optset.c b/lib/libsys/optset.c
index be65cfa9e..22a54bdfb 100644
--- a/lib/libsys/optset.c
+++ b/lib/libsys/optset.c
@@ -33,6 +33,7 @@ int len;
  */
   char *dst;
   int val;
+  int64_t val64;
 
   switch (entry->os_type) {
   case OPT_BOOL:
@@ -52,6 +53,15 @@ int len;
 
 	break;
 
+  case OPT_64INT:
+	if (len > 0)
+		val64 = (uint64_t) strtoull(ptr, NULL, entry->os_val);
+	else
+		val64 = 0;
+
+	*((uint64_t *) entry->os_ptr) = val64;
+
+	break;
   case OPT_INT:
 	if (len > 0)
 		val = (int) strtoul(ptr, NULL, entry->os_val);
diff --git a/test/blocktest/blocktest.c b/test/blocktest/blocktest.c
index 70c49431d..fee612f52 100644
--- a/test/blocktest/blocktest.c
+++ b/test/blocktest/blocktest.c
@@ -61,7 +61,7 @@ static int driver_deaths = 0;		/* number of restarts that we saw */
 /* Options supported by this driver. */
 static struct optset optset_table[] = {
 	{ "label",	OPT_STRING,	driver_label,	sizeof(driver_label) },
-	{ "minor",	OPT_INT,	&driver_minor,	10		     },
+	{ "minor",	OPT_64INT,	&driver_minor,	10		     },
 	{ "rw",		OPT_BOOL,	&may_write,	TRUE		     },
 	{ "ro",		OPT_BOOL,	&may_write,	FALSE		     },
 	{ "sector",	OPT_INT,	&sector_size,	10		     },