diff --git a/src/algorithms/signal_source/libs/fpga_buffer_monitor.cc b/src/algorithms/signal_source/libs/fpga_buffer_monitor.cc
index 136409f12..449579441 100644
--- a/src/algorithms/signal_source/libs/fpga_buffer_monitor.cc
+++ b/src/algorithms/signal_source/libs/fpga_buffer_monitor.cc
@@ -31,6 +31,7 @@
 #include <fstream>     // for string, ofstream
 #include <iostream>    // for cout
 #include <sys/mman.h>  // for mmap
+#include <unistd.h>    // for close
 #include <utility>     // for move
 
 
diff --git a/src/algorithms/signal_source/libs/fpga_dynamic_bit_selection.cc b/src/algorithms/signal_source/libs/fpga_dynamic_bit_selection.cc
index 933d8b77f..8cec947ef 100644
--- a/src/algorithms/signal_source/libs/fpga_dynamic_bit_selection.cc
+++ b/src/algorithms/signal_source/libs/fpga_dynamic_bit_selection.cc
@@ -25,6 +25,7 @@
 #include <fcntl.h>     // for open, O_RDWR, O_SYNC
 #include <iostream>    // for cout
 #include <sys/mman.h>  // for mmap
+#include <unistd.h>    // for close
 
 Fpga_dynamic_bit_selection::Fpga_dynamic_bit_selection(bool enable_rx1_band, bool enable_rx2_band)
     : d_map_base_freq_band_1(nullptr),
diff --git a/src/algorithms/signal_source/libs/fpga_switch.cc b/src/algorithms/signal_source/libs/fpga_switch.cc
index 4bcbe4dc9..b56f63bf5 100644
--- a/src/algorithms/signal_source/libs/fpga_switch.cc
+++ b/src/algorithms/signal_source/libs/fpga_switch.cc
@@ -25,6 +25,7 @@
 #include <fcntl.h>     // for open, O_RDWR, O_SYNC
 #include <iostream>    // for cout
 #include <sys/mman.h>  // for mmap
+#include <unistd.h>    // for close
 
 Fpga_Switch::Fpga_Switch(const std::string &device_name)
 {