diff --git a/Fat.h b/Fat.h
index ab16a7f..f056090 100644
--- a/Fat.h
+++ b/Fat.h
@@ -25,7 +25,7 @@
     static int doMount(const char *fsPath, const char *mountPoint, bool ro,
                        bool remount, int ownerUid, int ownerGid, int permMask,
                        bool createLost);
-    static int format(const char *fsPath);
+    static int format(const char *fsPath, unsigned int numSectors);
 };
 
 #endif