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 583fbfe0c..1802324c5 100644
--- a/src/algorithms/signal_source/libs/fpga_dynamic_bit_selection.cc
+++ b/src/algorithms/signal_source/libs/fpga_dynamic_bit_selection.cc
@@ -69,7 +69,7 @@ Fpga_dynamic_bit_selection::~Fpga_dynamic_bit_selection()
 }
 
 
-void Fpga_dynamic_bit_selection::bit_selection(void)
+void Fpga_dynamic_bit_selection::bit_selection()
 {
     // estimated signal power corresponding to frequency band 1
     uint32_t rx_signal_power1 = d_map_base1[1];
diff --git a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
index b0192f26e..c5b224f5f 100644
--- a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
+++ b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
@@ -1297,7 +1297,7 @@ int32_t dll_pll_veml_tracking_fpga::save_matfile() const
 }
 
 
-void dll_pll_veml_tracking_fpga::set_channel(uint32_t channel, std::string device_io_name)
+void dll_pll_veml_tracking_fpga::set_channel(uint32_t channel, const std::string& device_io_name)
 {
     gr::thread::scoped_lock l(d_setlock);
 
diff --git a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h
index 9233f2715..3a2c863a9 100644
--- a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h
+++ b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.h
@@ -66,7 +66,7 @@ public:
     /*!
      * \brief Set the channel number and configure some multicorrelator parameters
      */
-    void set_channel(uint32_t channel, std::string device_io_name);
+    void set_channel(uint32_t channel, const std::string& device_io_name);
 
     /*!
      * \brief This function is used with two purposes:
diff --git a/src/algorithms/tracking/libs/fpga_multicorrelator.cc b/src/algorithms/tracking/libs/fpga_multicorrelator.cc
index a962dfbe1..edb87a375 100644
--- a/src/algorithms/tracking/libs/fpga_multicorrelator.cc
+++ b/src/algorithms/tracking/libs/fpga_multicorrelator.cc
@@ -192,7 +192,7 @@ bool Fpga_Multicorrelator_8sc::free()
 }
 
 
-void Fpga_Multicorrelator_8sc::open_channel(std::string device_io_name, uint32_t channel)
+void Fpga_Multicorrelator_8sc::open_channel(const std::string& device_io_name, uint32_t channel)
 {
     std::cout << "trk device_io_name = " << device_io_name << '\n';
 
diff --git a/src/algorithms/tracking/libs/fpga_multicorrelator.h b/src/algorithms/tracking/libs/fpga_multicorrelator.h
index f67520f63..42fa151b9 100644
--- a/src/algorithms/tracking/libs/fpga_multicorrelator.h
+++ b/src/algorithms/tracking/libs/fpga_multicorrelator.h
@@ -91,7 +91,7 @@ public:
     /*!
      * \brief Open the FPGA device driver
      */
-    void open_channel(std::string device_io_name, uint32_t channel);
+    void open_channel(const std::string& device_io_name, uint32_t channel);
 
     /*!
      * \brief Set the initial sample number where the tracking process begins
diff --git a/src/core/libs/uio_fpga.cc b/src/core/libs/uio_fpga.cc
index 14156a654..647ec846e 100644
--- a/src/core/libs/uio_fpga.cc
+++ b/src/core/libs/uio_fpga.cc
@@ -32,7 +32,10 @@ int32_t get_uio_num(std::string uio_name)
     // search first digit
     for (; i < uio_name.length(); i++)
         {
-            if (isdigit(uio_name[i])) break;
+            if (isdigit(uio_name[i]))
+                {
+                    break;
+                }
         }
 
     // remove the first chars, which aren't digits
@@ -137,7 +140,7 @@ int my_strverscmp(const char *s1, const char *s2)
 }
 
 
-bool sort_directories(fs::directory_entry a, fs::directory_entry b)
+bool sort_directories(const fs::directory_entry &a, const fs::directory_entry &b)
 {
     int cmp = my_strverscmp(a.path().string().c_str(), b.path().string().c_str());
     return (cmp < 0);
@@ -166,7 +169,7 @@ int32_t find_uio_num(const std::string &device_name, uint32_t device_num)
                 {
                     std::string nametemp;
                     get_uio_name(uio_num, nametemp);
-                    if (device_name.compare(nametemp) == 0)
+                    if (device_name == nametemp)
                         {
                             if (uio_count == device_num)
                                 {