diff --git a/src/BulHit.cpp b/src/BulHit.cpp
index b6bb9f56..065d8659 100644
--- a/src/BulHit.cpp
+++ b/src/BulHit.cpp
@@ -7,7 +7,7 @@
 #include "NpChar.h"
 #include "Sound.h"
 
-void Vanish(BULLET *bul)
+static void Vanish(BULLET *bul)
 {
 	if (bul->code_bullet != 37 && bul->code_bullet != 38 && bul->code_bullet != 39)
 		PlaySoundObject(28, 1);
diff --git a/src/Game.cpp b/src/Game.cpp
index ccec7cae..25a64fa7 100644
--- a/src/Game.cpp
+++ b/src/Game.cpp
@@ -107,7 +107,7 @@ void PutNumber4(int x, int y, int value, BOOL bZero)
 	}
 }
 
-int ModeOpening(HWND hWnd)
+static int ModeOpening(HWND hWnd)
 {
 	int frame_x;
 	int frame_y;
@@ -223,7 +223,7 @@ int ModeOpening(HWND hWnd)
 	return 2;
 }
 
-int ModeTitle(HWND hWnd)
+static int ModeTitle(HWND hWnd)
 {
 	// Set rects
 	RECT rcTitle = {0, 0, 144, 40};
@@ -470,7 +470,7 @@ int ModeTitle(HWND hWnd)
 	return 3;
 }
 
-int ModeAction(HWND hWnd)
+static int ModeAction(HWND hWnd)
 {
 	int frame_x;
 	int frame_y;
diff --git a/src/Main.cpp b/src/Main.cpp
index 8db8aeee..c46cd1dc 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -70,7 +70,7 @@ void PutFramePerSecound(void)
 	}
 }
 
-unsigned long CountFramePerSecound(void)
+static unsigned long CountFramePerSecound(void)
 {
 	unsigned long current_tick;	// The original name for this variable is unknown
 	static BOOL first = TRUE;
diff --git a/src/MycHit.cpp b/src/MycHit.cpp
index 77cfe04d..9246d9bf 100644
--- a/src/MycHit.cpp
+++ b/src/MycHit.cpp
@@ -19,7 +19,7 @@ void ResetMyCharFlag(void)
 	gMC.flag = 0;
 }
 
-void PutlittleStar(void)
+static void PutlittleStar(void)
 {
 	if (!(gMC.cond & 2) && gMC.ym < -0x200)
 	{