diff --git a/userspace/Makefile b/userspace/Makefile
index 1c3e3fe..8a4f23f 100644
--- a/userspace/Makefile
+++ b/userspace/Makefile
@@ -1,3 +1,3 @@
-userccflags += -I$(src)/../include
+userccflags += -I$(src)/../include -g
 userprogs-always-y += vendor-reset
-vendor-reset-objs += vendor-reset.o
\ No newline at end of file
+vendor-reset-objs += vendor-reset.o ucommon.o
\ No newline at end of file
diff --git a/userspace/ucommon.c b/userspace/ucommon.c
new file mode 100644
index 0000000..ba83daf
--- /dev/null
+++ b/userspace/ucommon.c
@@ -0,0 +1,63 @@
+/*
+Vendor Reset - Vendor Specific Reset
+Copyright (C) 2020 Geoffrey McRae <geoff@hostfission.com>
+Copyright (C) 2020 Adam Madsen <adam@ajmadsen.com>
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "ucommon.h"
+
+int parse_dbdf(const char *dbdf_str, struct dbdf *out)
+{
+  char *dbdf, *tok;
+
+  if (!dbdf_str || !(dbdf = strdup(dbdf_str)))
+    return 1;
+
+  if (!(tok = strtok(dbdf, ":")))
+    goto err;
+
+  out->domain = 0;
+  out->bus = strtoul(tok, NULL, 16);
+
+  tok = strtok(NULL, ":");
+  if (strtok(NULL, ":"))
+  {
+    out->domain = out->bus;
+    out->bus = strtoul(tok, NULL, 16);
+    /* guaranteed to be okay */
+    tok += strlen(tok) + 1;
+  }
+
+  if (!(tok = strtok(tok, ".")))
+    goto err;
+
+  out->device = strtoul(tok, NULL, 16);
+
+  if (!(tok = strtok(NULL, ".")))
+    goto err;
+
+  out->function = strtoul(tok, NULL, 16);
+
+  free(dbdf);
+  return 0;
+
+err:
+  free(dbdf);
+  return 1;
+}
\ No newline at end of file
diff --git a/userspace/ucommon.h b/userspace/ucommon.h
new file mode 100644
index 0000000..14df46c
--- /dev/null
+++ b/userspace/ucommon.h
@@ -0,0 +1,36 @@
+/*
+Vendor Reset - Vendor Specific Reset
+Copyright (C) 2020 Geoffrey McRae <geoff@hostfission.com>
+Copyright (C) 2020 Adam Madsen <adam@ajmadsen.com>
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#ifndef __VENDOR_RESET_UCOMMON_H__
+#define __VENDOR_RESET_UCOMMON_H__
+
+struct dbdf
+{
+  int domain;
+  int bus;
+  int device;
+  int function;
+};
+
+/*
+ * parse [domain:]bus:device.fn type addresses
+ */
+extern int parse_dbdf(const char *dbdf_str, struct dbdf *out);
+
+#endif
\ No newline at end of file
diff --git a/userspace/vendor-reset.c b/userspace/vendor-reset.c
index bafb5d6..7120191 100644
--- a/userspace/vendor-reset.c
+++ b/userspace/vendor-reset.c
@@ -1,6 +1,7 @@
 /*
 Vendor Reset - Vendor Specific Reset
 Copyright (C) 2020 Geoffrey McRae <geoff@hostfission.com>
+Copyright (C) 2020 Adam Madsen <adam@ajmadsen.com>
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -22,24 +23,30 @@ Place, Suite 330, Boston, MA 02111-1307 USA
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include "vendor-reset.h"
+#include "ucommon.h"
 
-int main(int argc, char * argv[])
+void help_(const char *prog);
+
+void help_(const char *prog)
+{
+  fprintf(stderr,
+          "Usage:\n"
+          "  %s [domain:]bus:dev.fn\n",
+          prog);
+  exit(1);
+}
+#define help() help_(argv[0])
+
+int main(int argc, char *argv[])
 {
   int ret;
+  struct dbdf devref;
 
-  if (argc < 4)
-  {
-    fprintf(stderr,
-      "Usage:\n"
-      "  %s <domain> <bus> <devfn>\n",
-      argv[0]
-    );
-    return -1;
-  }
+  if (argc < 2)
+    help();
 
-  int domain = atoi(argv[1]);
-  int bus    = atoi(argv[2]);
-  int devfn  = atoi(argv[3]);
+  if (parse_dbdf(argv[1], &devref))
+    help();
 
   int fd = open("/dev/vendor_reset", O_RDWR);
   if (fd < 0)
@@ -48,11 +55,10 @@ int main(int argc, char * argv[])
     return fd;
   }
 
-  struct vendor_reset_ioctl dev =
-  {
-    .domain = domain,
-    .bus    = bus,
-    .devfn  = devfn
+  struct vendor_reset_ioctl dev = {
+    .domain = devref.domain,
+    .bus = devref.bus,
+    .devfn = ((devref.device & 0x1f) << 3) | (devref.function & 0x07),
   };
 
   ret = ioctl(fd, VENDOR_RESET_RESET, &dev);