diff --git a/Volume.cpp b/Volume.cpp
index 21b66b1..9bf86bb 100644
--- a/Volume.cpp
+++ b/Volume.cpp
@@ -250,7 +250,9 @@
     bool formatEntireDevice = (mPartIdx == -1);
     char devicePath[255];
     dev_t diskNode = getDiskDevice();
-    dev_t partNode = MKDEV(MAJOR(diskNode), (formatEntireDevice ? 1 : mPartIdx));
+    dev_t partNode =
+        MKDEV(MAJOR(diskNode),
+              MINOR(diskNode) + (formatEntireDevice ? 1 : mPartIdx));
 
     setState(Volume::State_Formatting);