diff --git a/L1Trigger/TrackFindingTracklet/interface/Stub.h b/L1Trigger/TrackFindingTracklet/interface/Stub.h
index 90c8f7f1dbd80..de7f78ca6ebeb 100644
--- a/L1Trigger/TrackFindingTracklet/interface/Stub.h
+++ b/L1Trigger/TrackFindingTracklet/interface/Stub.h
@@ -43,7 +43,11 @@ namespace trklet {
       unsigned int nbitsfinephi = 8;
       FPGAWord finephi(
           phicorr_.bits(phicorr_.nbits() - nbitsfinephi, nbitsfinephi), nbitsfinephi, true, __LINE__, __FILE__);
-      return str() + "|" + stubindex_.str() + "|" + finephi.str();
+      if (layer_.value() == -1) {
+        return str() + "|" + negdisk_.str() + "|" + stubindex_.str() + "|" + finephi.str();
+      } else {
+        return str() + "|" + stubindex_.str() + "|" + finephi.str();
+      }
     }
 
     FPGAWord allStubIndex() const { return stubindex_; }
@@ -59,6 +63,7 @@ namespace trklet {
 
     const FPGAWord& r() const { return r_; }
     const FPGAWord& z() const { return z_; }
+    const FPGAWord& negdisk() const { return negdisk_; }
     const FPGAWord& phi() const { return phi_; }
     const FPGAWord& phicorr() const { return phicorr_; }
     const FPGAWord& alpha() const { return alpha_; }
@@ -87,6 +92,7 @@ namespace trklet {
     FPGAWord disk_;
     FPGAWord r_;
     FPGAWord z_;
+    FPGAWord negdisk_;
     FPGAWord phi_;
     FPGAWord alpha_;
 
diff --git a/L1Trigger/TrackFindingTracklet/src/Stub.cc b/L1Trigger/TrackFindingTracklet/src/Stub.cc
index 8359d17894966..68c722c7102a6 100644
--- a/L1Trigger/TrackFindingTracklet/src/Stub.cc
+++ b/L1Trigger/TrackFindingTracklet/src/Stub.cc
@@ -77,6 +77,8 @@ Stub::Stub(L1TStub& stub, Settings const& settings, Globals& globals) : settings
       alpha_.set(newalpha, nalphabits, false, __LINE__, __FILE__);
       nrbits = 4;
     }
+    int negdisk = (disk < 0) ? 1 : 0;
+    negdisk_.set(negdisk, 1, true, __LINE__, __FILE__);
   } else {
     disk_.set(0, 4, false, __LINE__, __FILE__);
     layer_.set(layerdisk_, 3, true, __LINE__, __FILE__);