diff --git a/cpr.c b/cpr.c
index f2e35c5..c2e14ff 100644
--- a/cpr.c
+++ b/cpr.c
@@ -47,6 +47,8 @@
 //   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 //   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include "cpr.h"
+
 #include <math.h>
 #include <stdio.h>
 
diff --git a/dump1090.c b/dump1090.c
index 2506e8c..e45c370 100644
--- a/dump1090.c
+++ b/dump1090.c
@@ -102,7 +102,7 @@ void receiverPositionChanged(float lat, float lon, float alt)
 //
 // =============================== Initialization ===========================
 //
-void modesInitConfig(void) {
+static void modesInitConfig(void) {
     // Default everything to zero/NULL
     memset(&Modes, 0, sizeof(Modes));
 
@@ -127,7 +127,7 @@ void modesInitConfig(void) {
 //
 //=========================================================================
 //
-void modesInit(void) {
+static void modesInit(void) {
     int i;
 
     pthread_mutex_init(&Modes.data_mutex,NULL);
@@ -216,7 +216,7 @@ void modesInit(void) {
 // without caring about data acquisition
 //
 
-void *readerThreadEntryPoint(void *arg)
+static void *readerThreadEntryPoint(void *arg)
 {
     MODES_NOTUSED(arg);
 
@@ -237,7 +237,7 @@ void *readerThreadEntryPoint(void *arg)
 // Get raw IQ samples and filter everything is < than the specified level
 // for more than 256 samples in order to reduce example file size
 //
-void snipMode(int level) {
+static void snipMode(int level) {
     int i, q;
     uint64_t c = 0;
 
@@ -255,7 +255,7 @@ void snipMode(int level) {
 //
 // ================================ Main ====================================
 //
-void showHelp(void) {
+static void showHelp(void) {
 
     printf("-----------------------------------------------------------------------------\n");
     printf("| dump1090 ModeS Receiver     %45s |\n", MODES_DUMP1090_VARIANT " " MODES_DUMP1090_VERSION);
@@ -354,7 +354,7 @@ static void display_total_stats(void)
 // perform tasks we need to do continuously, like accepting new clients
 // from the net, refreshing the screen in interactive mode, and so forth
 //
-void backgroundTasks(void) {
+static void backgroundTasks(void) {
     static uint64_t next_stats_display;
     static uint64_t next_stats_update;
     static uint64_t next_json, next_history;
diff --git a/net_io.c b/net_io.c
index 6375f01..1de5851 100644
--- a/net_io.c
+++ b/net_io.c
@@ -790,7 +790,7 @@ void modesQueueOutput(struct modesMessage *mm, struct aircraft *a) {
 }
 
 // Decode a little-endian IEEE754 float (binary32)
-float ieee754_binary32_le_to_float(uint8_t *data)
+static float ieee754_binary32_le_to_float(uint8_t *data)
 {
     double sign = (data[3] & 0x80) ? -1.0 : 1.0;
     int16_t raw_exponent = ((data[3] & 0x7f) << 1) | ((data[2] & 0x80) >> 7);
diff --git a/sdr_rtlsdr.c b/sdr_rtlsdr.c
index f2fc30b..b0299ce 100644
--- a/sdr_rtlsdr.c
+++ b/sdr_rtlsdr.c
@@ -267,7 +267,7 @@ bool rtlsdrOpen(void) {
 
 static struct timespec rtlsdr_thread_cpu;
 
-void rtlsdrCallback(unsigned char *buf, uint32_t len, void *ctx) {
+static void rtlsdrCallback(unsigned char *buf, uint32_t len, void *ctx) {
     struct mag_buf *outbuf;
     struct mag_buf *lastbuf;
     uint32_t slen;
diff --git a/track.c b/track.c
index e1bae95..d18b11d 100644
--- a/track.c
+++ b/track.c
@@ -61,7 +61,7 @@ uint32_t modeAC_age[4096];
 // Return a new aircraft structure for the linked list of tracked
 // aircraft
 //
-struct aircraft *trackCreateAircraft(struct modesMessage *mm) {
+static struct aircraft *trackCreateAircraft(struct modesMessage *mm) {
     static struct aircraft zeroAircraft;
     struct aircraft *a = (struct aircraft *) malloc(sizeof(*a));
     int i;
@@ -142,7 +142,7 @@ struct aircraft *trackCreateAircraft(struct modesMessage *mm) {
 // Return the aircraft with the specified address, or NULL if no aircraft
 // exists with this address.
 //
-struct aircraft *trackFindAircraft(uint32_t addr) {
+static struct aircraft *trackFindAircraft(uint32_t addr) {
     struct aircraft *a = Modes.aircrafts;
 
     while(a) {
diff --git a/view1090.c b/view1090.c
index ae925f5..33f9a63 100644
--- a/view1090.c
+++ b/view1090.c
@@ -31,7 +31,7 @@
 //
 // ============================= Utility functions ==========================
 //
-void sigintHandler(int dummy) {
+static void sigintHandler(int dummy) {
     MODES_NOTUSED(dummy);
     signal(SIGINT, SIG_DFL);  // reset signal handler - bit extra safety
     Modes.exit = 1;           // Signal to threads that we are done
@@ -48,7 +48,7 @@ void receiverPositionChanged(float lat, float lon, float alt)
 //
 // =============================== Initialization ===========================
 //
-void view1090InitConfig(void) {
+static void view1090InitConfig(void) {
     // Default everything to zero/NULL
     memset(&Modes,    0, sizeof(Modes));
 
@@ -61,7 +61,7 @@ void view1090InitConfig(void) {
 //
 //=========================================================================
 //
-void view1090Init(void) {
+static void view1090Init(void) {
 
     pthread_mutex_init(&Modes.data_mutex,NULL);
     pthread_cond_init(&Modes.data_cond,NULL);
@@ -105,7 +105,7 @@ void view1090Init(void) {
 //
 // ================================ Main ====================================
 //
-void showHelp(void) {
+static void showHelp(void) {
     printf(
 "-----------------------------------------------------------------------------\n"
 "| view1090 ModeS Viewer       %45s |\n"
@@ -129,7 +129,7 @@ void showHelp(void) {
     );
 }
 
-void sendSettings(struct client *c)
+static void sendSettings(struct client *c)
 {
     sendBeastSettings(c, "CdV"); // Beast binary format, no filters, verbatim mode on
     sendBeastSettings(c, Modes.mode_ac ? "J" : "j");  // Mode A/C on or off