diff --git a/app/src/adb/adb_parser.c b/app/src/adb/adb_parser.c
index e7358403..66bb1854 100644
--- a/app/src/adb/adb_parser.c
+++ b/app/src/adb/adb_parser.c
@@ -7,7 +7,7 @@
 #include "util/log.h"
 #include "util/str.h"
 
-bool
+static bool
 sc_adb_parse_device(char *line, struct sc_adb_device *device) {
     // One device line looks like:
     // "0123456789abcdef	device usb:2-1 product:MyProduct model:MyModel "
diff --git a/app/src/main.c b/app/src/main.c
index d582c5ae..6050de11 100644
--- a/app/src/main.c
+++ b/app/src/main.c
@@ -23,7 +23,7 @@
 #include "util/str.h"
 #endif
 
-int
+static int
 main_scrcpy(int argc, char *argv[]) {
 #ifdef _WIN32
     // disable buffering, we want logs immediately
diff --git a/app/src/scrcpy.c b/app/src/scrcpy.c
index 968629a2..f2893230 100644
--- a/app/src/scrcpy.c
+++ b/app/src/scrcpy.c
@@ -90,7 +90,7 @@ push_event(uint32_t type, const char *name) {
 #define PUSH_EVENT(TYPE) push_event(TYPE, # TYPE)
 
 #ifdef _WIN32
-BOOL WINAPI windows_ctrl_handler(DWORD ctrl_type) {
+static BOOL WINAPI windows_ctrl_handler(DWORD ctrl_type) {
     if (ctrl_type == CTRL_C_EVENT) {
         PUSH_EVENT(SDL_QUIT);
         return TRUE;
diff --git a/app/tests/test_bytebuf.c b/app/tests/test_bytebuf.c
index c85e79ec..8e9d7c57 100644
--- a/app/tests/test_bytebuf.c
+++ b/app/tests/test_bytebuf.c
@@ -5,7 +5,7 @@
 
 #include "util/bytebuf.h"
 
-void test_bytebuf_simple(void) {
+static void test_bytebuf_simple(void) {
     struct sc_bytebuf buf;
     uint8_t data[20];
 
@@ -34,7 +34,7 @@ void test_bytebuf_simple(void) {
     sc_bytebuf_destroy(&buf);
 }
 
-void test_bytebuf_boundaries(void) {
+static void test_bytebuf_boundaries(void) {
     struct sc_bytebuf buf;
     uint8_t data[20];
 
@@ -71,7 +71,7 @@ void test_bytebuf_boundaries(void) {
     sc_bytebuf_destroy(&buf);
 }
 
-void test_bytebuf_two_steps_write(void) {
+static void test_bytebuf_two_steps_write(void) {
     struct sc_bytebuf buf;
     uint8_t data[20];