diff --git a/DataFormats/GEMDigi/interface/GEMVFAT.h b/DataFormats/GEMDigi/interface/GEMVFAT.h
index 94811bac22e2b..79820cd93cd1b 100644
--- a/DataFormats/GEMDigi/interface/GEMVFAT.h
+++ b/DataFormats/GEMDigi/interface/GEMVFAT.h
@@ -16,7 +16,8 @@ class GEMVFAT {
       // is half-full, so it's like a warning
       uint64_t vc : 1;   /// VFAT CRC Error
       uint64_t : 7;      // unused
-      uint64_t pos : 8;  // VFAT position on chamber, 5 used in GE11 but more is needed for phase2
+      uint64_t pos : 5;  // VFAT position on chamber, 5 used in GE11 but more is needed for phase2
+      uint64_t : 3;      // unused
     };
     // v2 dataformat
     struct {