diff --git a/Volume.cpp b/Volume.cpp
index ca56d1c..0baf008 100644
--- a/Volume.cpp
+++ b/Volume.cpp
@@ -252,7 +252,7 @@
     dev_t diskNode = getDiskDevice();
     dev_t partNode =
         MKDEV(MAJOR(diskNode),
-              MINOR(diskNode) + (formatEntireDevice ? 1 : mPartIdx));
+              MINOR(diskNode) + (formatEntireDevice ? 0 : mPartIdx));
 
     setState(Volume::State_Formatting);