diff --git a/src/cmd2F.c b/src/cmd2F.c
index 86d5497..16bc18f 100644
--- a/src/cmd2F.c
+++ b/src/cmd2F.c
@@ -42,11 +42,14 @@
 #include "ald_manager.h"
 #include "LittleEndian.h"
 #include "hacks.h"
+#include "filecheck.h"
 
 /* 選択 Window OPEN 時 callback */
 static int cb_sel_init_page = 0;
 static int cb_sel_init_address = 0;
 
+static const char REGREADSTRING_RESULT[] = "*regReadString*";
+
 extern INPUTSTRING_PARAM mi_param;
 
 extern void commandH();
@@ -1441,7 +1444,10 @@ void commands2F87() {
 	int eBaneStrNum   = getCaliValue();
 	int eResultStrNum = getCaliValue();
 	int *vResult      = getCaliVariable();
-	
+
+	// This command is used to check if the game is installed, so we always
+	// return 1 with the dummy string REGREADSTRING_RESULT.
+	svar_set(eResultStrNum, REGREADSTRING_RESULT);
 	*vResult = 1;
 	
 	DEBUG_COMMAND("regReadString %d,%d,%d,%d:",
@@ -1451,8 +1457,17 @@ void commands2F87() {
 void commands2F88() {
 	int eFileNameStrNum = getCaliValue();
 	int *vResult        = getCaliVariable();
-	
-	*vResult = 1;
+
+	const char *fname = svar_get(eFileNameStrNum);
+	if (strcmp(fname, REGREADSTRING_RESULT) == 0) {
+		// If this command is called with the result of regReadString, the game
+		// is checking if the game CD is inserted. We return 1 in this case.
+		*vResult = 1;
+	} else {
+		char *fname_utf8 = sjis2utf(fname);
+		*vResult = fc_exists(fname_utf8) ? 1 : 0;
+		free(fname_utf8);
+	}
 	
 	DEBUG_COMMAND("fileCheckExist %d,%d:", eFileNameStrNum, *vResult);
 }
diff --git a/src/filecheck.c b/src/filecheck.c
index 7cdb1af..9c5bba7 100644
--- a/src/filecheck.c
+++ b/src/filecheck.c
@@ -29,11 +29,10 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <dirent.h>
+#include <unistd.h>
 #ifdef _WIN32
 #include <direct.h>
 #include <windows.h>
-#undef min
-#undef max
 #endif
 
 #include "filecheck.h"
@@ -126,6 +125,18 @@ char *fc_get_path(const char *fname_utf8) {
 	return get_fullpath(saveDataPath, fname_utf8);
 }
 
+bool fc_exists(const char *fname_utf8)
+{
+	char *path = fc_get_path(fname_utf8);
+	wchar_t wpath[PATH_MAX + 1];
+	bool result = false;
+	if (MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, path, -1, wpath, PATH_MAX + 1)) {
+		result = _waccess(wpath, F_OK) != -1;
+	}
+	free(path);
+	return result;
+}
+
 FILE *fc_open(const char *fname_utf8, char type) {
 	char *path = fc_get_path(fname_utf8);
 	FILE *fp = fopen_utf8(path, type);
@@ -162,6 +173,14 @@ char *fc_get_path(const char *fname_utf8) {
 	return get_fullpath(saveDataPath, fname_utf8);
 }
 
+bool fc_exists(const char *fname_utf8)
+{
+	char *path = fc_get_path(fname_utf8);
+	bool result = access(path, F_OK) != -1;
+	free(path);
+	return result;
+}
+
 FILE *fc_open(const char *fname_utf8, char type) {
 	char *fullpath = fc_search(fname_utf8, saveDataPath);
 	if (!fullpath) {
diff --git a/src/filecheck.h b/src/filecheck.h
index 1135419..85e3d2d 100644
--- a/src/filecheck.h
+++ b/src/filecheck.h
@@ -24,9 +24,12 @@
 #ifndef __FILECHECK_H__
 #define __FILECHECK_H__
 
-extern void fc_init(const char *name);
-extern char *fc_get_path(const char *fname_utf8);
-extern FILE *fc_open(const char *fname_utf8, char type);
-extern void fc_backup_oldfile(const char *filename);
+#include <stdbool.h>
+
+void fc_init(const char *name);
+char *fc_get_path(const char *fname_utf8);
+bool fc_exists(const char *fname_utf8);
+FILE *fc_open(const char *fname_utf8, char type);
+void fc_backup_oldfile(const char *filename);
 
 #endif /* !__FILECHECK_H__ */