diff --git a/fpga/hls/jf_conversion.cpp b/fpga/hls/jf_conversion.cpp
index 035538c8..891386c8 100644
--- a/fpga/hls/jf_conversion.cpp
+++ b/fpga/hls/jf_conversion.cpp
@@ -139,7 +139,7 @@ void jf_conversion(STREAM_512 &data_in, STREAM_512 &data_out,
 
     ap_uint<64> mode = ACT_REG_MODE(packet_in.data);
     ap_uint<1> conversion = (mode & MODE_CONV) ? 1 : 0;
-    ap_uint<5> modules = ACT_REG_NMODULES(packet_in.data);
+    ap_uint<6> modules = ACT_REG_NMODULES(packet_in.data) + 1;
     ap_uint<32> in_one_over_energy = ACT_REG_ONE_OVER_ENERGY(packet_in.data);
     ap_uint<5> storage_cells = ACT_REG_NSTORAGE_CELLS(packet_in.data);
 
diff --git a/receiver/FPGAAcquisitionDevice.cpp b/receiver/FPGAAcquisitionDevice.cpp
index 32153691..41e8bbc3 100644
--- a/receiver/FPGAAcquisitionDevice.cpp
+++ b/receiver/FPGAAcquisitionDevice.cpp
@@ -202,7 +202,7 @@ void FPGAAcquisitionDevice::FillActionRegister(const DiffractionExperiment& x, D
     std::uniform_int_distribution<uint16_t> dist;
     data_collection_id = dist(rd);
 
-    job.nmodules            = x.GetModulesNum(data_stream);
+    job.nmodules            = x.GetModulesNum(data_stream) - 1;
     job.nframes             = x.GetFrameNum();
     job.one_over_energy     = std::lround((1<<20)/ x.GetPhotonEnergy_keV());
     job.nstorage_cells      = x.GetStorageCellNumber() - 1;