diff --git a/src/asm.c b/src/asm.c
index b33a3e2..5da6220 100644
--- a/src/asm.c
+++ b/src/asm.c
@@ -60,7 +60,6 @@ static const AsmPluginDescription _asm_plugin_description[APT_COUNT] =
 
 /* prototypes */
 static char const * _asm_guess_arch(void);
-static char const * _asm_guess_format(void);
 
 static int _asm_open(Asm * a, char const * outfile);
 
@@ -72,6 +71,9 @@ Asm * asm_new(char const * arch, char const * format)
 {
 	Asm * a;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(\"%s\", \"%s\")\n", __func__, arch, format);
+#endif
 	if((a = object_new(sizeof(*a))) == NULL)
 		return NULL;
 	a->arch = (arch != NULL) ? string_new(arch) : NULL;
@@ -90,6 +92,9 @@ Asm * asm_new(char const * arch, char const * format)
 /* asm_delete */
 void asm_delete(Asm * a)
 {
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s()\n", __func__);
+#endif
 	if(a->code != NULL)
 		code_delete(a->code);
 	string_delete(a->format);
@@ -215,17 +220,6 @@ int asm_guess_arch(Asm * a)
 }
 
 
-/* asm_guess_format */
-int asm_guess_format(Asm * a)
-{
-	char const * format;
-
-	if((format = _asm_guess_format()) == NULL)
-		return -1;
-	return asm_set_format(a, format);
-}
-
-
 /* asm_instruction */
 int asm_instruction(Asm * a, char const * name, unsigned int operands_cnt, ...)
 {
@@ -340,14 +334,6 @@ static char const * _asm_guess_arch(void)
 }
 
 
-/* asm_guess_format */
-static char const * _asm_guess_format(void)
-{
-	/* FIXME really guess from known/guessed architecture plug-in */
-	return "elf";
-}
-
-
 /* asm_open */
 static int _asm_open(Asm * a, char const * outfile)
 {
@@ -356,8 +342,6 @@ static int _asm_open(Asm * a, char const * outfile)
 
 	if(arch == NULL && (arch = _asm_guess_arch()) == NULL)
 		return -1;
-	if(format == NULL)
-		format = _asm_guess_format();
 	if(a->code != NULL)
 		return -error_set_code(1, "%s: Operation in progress",
 				code_get_filename(a->code));
diff --git a/src/code.c b/src/code.c
index 6e1749f..135082b 100644
--- a/src/code.c
+++ b/src/code.c
@@ -94,14 +94,16 @@ Code * code_new(char const * arch, char const * format)
 {
 	Code * code;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s(\"%s\", \"%s\")\n", __func__, arch, format);
+#endif
 	if((code = object_new(sizeof(*code))) == NULL)
 		return NULL;
 	memset(code, 0, sizeof(*code));
-	if((code->arch = arch_new(arch)) != NULL && format == NULL)
-		format = arch_get_format(code->arch);
+	code->arch = arch_new(arch);
 	if(format != NULL)
 		code->format = format_new(format);
-	if(code->arch == NULL || code->format == NULL)
+	if(code->arch == NULL)
 	{
 		code_delete(code);
 		return NULL;
@@ -212,6 +214,9 @@ int code_delete(Code * code)
 {
 	int ret = 0;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s()\n", __func__);
+#endif
 	if(code->format != NULL)
 		format_delete(code->format);
 	if(code->arch != NULL)
@@ -303,8 +308,12 @@ int code_close(Code * code)
 {
 	int ret = 0;
 
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s()\n", __func__);
+#endif
 	ret |= arch_exit(code->arch);
-	ret |= format_exit(code->format);
+	if(code->format != NULL)
+		ret |= format_exit(code->format);
 	if(code->fp != NULL && fclose(code->fp) != 0 && ret == 0)
 		ret |= -error_set_code(1, "%s: %s", code->filename,
 				strerror(errno));
@@ -402,7 +411,10 @@ int code_open(Code * code, char const * filename)
 		return -error_set_code(1, "%s: %s", filename, strerror(errno));
 	if(arch_init(code->arch, code->filename, code->fp) == 0)
 	{
-		if(format_init(code->format, arch_get_name(code->arch),
+		if(code->format == NULL)
+			code->format = format_new(arch_get_format(code->arch));
+		if(code->format != NULL && format_init(code->format,
+					arch_get_name(code->arch),
 					code->filename, code->fp) == 0)
 			return 0;
 		arch_exit(code->arch);
diff --git a/src/deasm.c b/src/deasm.c
index 18a29a6..8e9d1bc 100644
--- a/src/deasm.c
+++ b/src/deasm.c
@@ -30,8 +30,7 @@
 /* prototypes */
 static int _deasm(char const * arch, char const * format, char const * filename,
 		int raw);
-static int _deasm_buffer(char const * arch, char const * format,
-		char const * buffer, size_t size);
+static int _deasm_buffer(char const * arch, char const * buffer, size_t size);
 static int _deasm_string(char const * arch, char const * format,
 		char const * string);
 static int _deasm_list(void);
@@ -59,15 +58,14 @@ static int _deasm(char const * arch, char const * format, char const * filename,
 
 
 /* deasm_buffer */
-static int _deasm_buffer(char const * arch, char const * format,
-		char const * buffer, size_t size)
+static int _deasm_buffer(char const * arch, char const * buffer, size_t size)
 {
 	Asm * a;
 
 #ifdef DEBUG
 	fprintf(stderr, "DEBUG: %s()\n", __func__);
 #endif
-	if((a = asm_new(arch, format)) == NULL)
+	if((a = asm_new(arch, NULL)) == NULL)
 		return -1;
 	if(asm_deassemble(a, buffer, size) != 0)
 		error_print("deasm");
@@ -111,7 +109,7 @@ static int _deasm_string(char const * arch, char const * format,
 		}
 	}
 	s[j] = '\0'; /* not really necessary */
-	ret = _deasm_buffer(arch, format, s, j);
+	ret = _deasm_buffer(arch, s, j);
 	free(s);
 	return ret;
 }
@@ -150,7 +148,7 @@ static int _deasm_list(void)
 static int _usage(void)
 {
 	fputs("Usage: deasm [-a arch][-f format] filename\n"
-"       deasm [-a arch][-f format] -s string\n"
+"       deasm [-a arch] -s string\n"
 "       deasm -l\n", stderr);
 	return 1;
 }
diff --git a/src/format.c b/src/format.c
index 5e7b2b4..548d0db 100644
--- a/src/format.c
+++ b/src/format.c
@@ -105,6 +105,10 @@ Format * format_new(char const * format)
 /* format_delete */
 void format_delete(Format * format)
 {
+#ifdef DEBUG
+	fprintf(stderr, "DEBUG: %s()\n", __func__);
+#endif
+	format_exit(format);
 	plugin_delete(format->handle);
 	object_delete(format);
 }
@@ -190,6 +194,8 @@ int format_init(Format * format, char const * arch, char const * filename,
 	fprintf(stderr, "DEBUG: %s(\"%s\", %p)\n", __func__, filename,
 			(void *)fp);
 #endif
+	if(format->plugin->helper != NULL)
+		format_exit(format);
 	format->filename = filename;
 	format->fp = fp;
 	format->plugin->helper = &format->helper;