diff --git a/checkpoint.cpp b/checkpoint.cpp
deleted file mode 100644
index b67132e..0000000
--- a/checkpoint.cpp
+++ /dev/null
@@ -1,58 +0,0 @@
-#include <stdint.h>
-#include <stdio.h>
-#include <string.h>
-#include "hardware.h"
-#include "serialio.h"
-#include "filer.h"
-#include "checkpoint.h"
-
-#if defined(USE_SD)
-#include <SD.h>
-#elif defined(USE_SPIFFS)
-#include <SPIFFS.h>
-#elif defined(ESP8266)
-#include <FS.h>
-#endif
-
-static char buf[32];
-static char chkpt[] = { "CHKPOINT" };
-static int cpid = 0;
-
-const char *checkpoint(filer &f, const char *dir) {
-#if defined(USE_SD) || defined(USE_SPIFFS) || defined(ESP8266)
-	f.stop();
-	snprintf(buf, sizeof(buf), "%s%s.%03d", dir, chkpt, cpid++);
-
-#if defined(USE_SD)
-	File file = SD.open(buf, O_WRITE | O_CREAT | O_TRUNC);
-#elif defined(USE_SPIFFS)
-	File file = SPIFFS.open(buf, FILE_WRITE);
-#else
-	File file = SPIFFS.open(buf, "w");
-#endif
-	hardware_checkpoint(file);
-	file.close();
-	f.start(dir);
-#endif
-	return buf;
-}
-
-void restore(filer &f, const char *dir, const char *filename) {
-#if defined(USE_SD) || defined(USE_SPIFFS) || defined(ESP8266)
-	f.stop();
-	snprintf(buf, sizeof(buf), "%s%s", dir, filename);
-
-#if defined(USE_SD)
-	File file = SD.open(buf, O_READ);
-#elif defined(USE_SPIFFS)
-	File file = SPIFFS.open(buf, FILE_READ);
-#else
-	File file = SPIFFS.open(buf, "r");
-#endif
-	hardware_restore(file);
-	file.close();
-	int n = sscanf(buf + strlen(dir), "%[A-Z0-9].%d", chkpt, &cpid);
-	cpid = (n == 1)? 0: cpid+1;
-#endif
-	f.start(dir);
-}
diff --git a/checkpoint.h b/checkpoint.h
deleted file mode 100644
index 2e95576..0000000
--- a/checkpoint.h
+++ /dev/null
@@ -1,8 +0,0 @@
-#ifndef __CHECKPOINT_H__
-#define __CHECKPOINT_H__
-
-// utility checkpoint functions
-const char *checkpoint(filer &f, const char *dir);
-void restore(filer &f, const char *dir, const char *filename);
-
-#endif
diff --git a/filer.cpp b/filer.cpp
index 1edae58..18716e8 100644
--- a/filer.cpp
+++ b/filer.cpp
@@ -1,3 +1,4 @@
+#include <Arduino.h>
 #include <stdint.h>
 #include "hardware.h"
 
@@ -19,15 +20,16 @@ static File file, dir;
 #elif defined(USE_FS)
 static File file;
 static Dir dir;
-static const char *programs;
 #endif
 
+static const char *programs;
+
 #define STORAGE defined(USE_SD) || defined(USE_SPIFFS) || defined(USE_FS)
 
 bool flash_filer::start(const char *programs)
 {
-#if defined(USE_FS)
 	::programs = programs;
+#if defined(USE_FS)
 	dir = SPIFFS.openDir(programs);
 #elif defined(DISK)
 	dir = DISK.open(programs);
@@ -101,3 +103,46 @@ const char *flash_filer::rewind() {
 #endif
 	return advance();
 }
+
+static char buf[32];
+static char chkpt[] = { "CHKPOINT" };
+static int cpid = 0;
+
+const char *flash_filer::checkpoint() {
+#if defined(USE_SD) || defined(USE_SPIFFS) || defined(ESP8266)
+	stop();
+	snprintf(buf, sizeof(buf), "%s%s.%03d", ::programs, chkpt, cpid++);
+
+#if defined(USE_SD)
+	File file = SD.open(buf, O_WRITE | O_CREAT | O_TRUNC);
+#elif defined(USE_SPIFFS)
+	File file = SPIFFS.open(buf, FILE_WRITE);
+#else
+	File file = SPIFFS.open(buf, "w");
+#endif
+	hardware_checkpoint(file);
+	file.close();
+	start(::programs);
+#endif
+	return buf;
+}
+
+void flash_filer::restore(const char *filename) {
+#if defined(USE_SD) || defined(USE_SPIFFS) || defined(ESP8266)
+	stop();
+	snprintf(buf, sizeof(buf), "%s%s", ::programs, filename);
+
+#if defined(USE_SD)
+	File file = SD.open(buf, O_READ);
+#elif defined(USE_SPIFFS)
+	File file = SPIFFS.open(buf, FILE_READ);
+#else
+	File file = SPIFFS.open(buf, "r");
+#endif
+	hardware_restore(file);
+	file.close();
+	int n = sscanf(buf + strlen(::programs), "%[A-Z0-9].%d", chkpt, &cpid);
+	cpid = (n == 1)? 0: cpid+1;
+#endif
+	start(::programs);
+}
diff --git a/filer.h b/filer.h
index 491e180..a300efa 100644
--- a/filer.h
+++ b/filer.h
@@ -6,6 +6,9 @@ public:
 	virtual const char *advance() =0;
 	virtual const char *rewind() =0;
 
+	virtual const char *checkpoint() =0;
+	virtual void restore(const char *) = 0;
+
 	virtual bool start(const char *) =0;
 	virtual void stop() =0;
 };
@@ -17,6 +20,9 @@ public:
 	const char *advance();
 	const char *rewind();
 
+	const char *checkpoint();
+	void restore(const char *);
+
 	bool start(const char *);
 	void stop();
 	
diff --git a/r65emu.h b/r65emu.h
index 2ab8013..0113082 100644
--- a/r65emu.h
+++ b/r65emu.h
@@ -13,7 +13,6 @@
 #include "filer.h"
 #include "timed.h"
 #include "hardware.h"
-#include "checkpoint.h"
 #include "sound_dac.h"
 #include "sound_pwm.h"