diff --git a/src/libopensc/pkcs15.c b/src/libopensc/pkcs15.c
index 258131b4..bd32ad63 100644
--- a/src/libopensc/pkcs15.c
+++ b/src/libopensc/pkcs15.c
@@ -183,7 +183,7 @@ int sc_pkcs15_create_tokeninfo(struct sc_pkcs15_card *card)
 	int r;
 	u8 *buf;
 	size_t buflen;
-	u8 line[10240];
+	char line[10240];
 	
 	r = encode_tokeninfo(card, &buf, &buflen);
 	if (r) {
@@ -308,7 +308,7 @@ int sc_pkcs15_create_dir(struct sc_pkcs15_card *p15card)
 	u8 *buf;
 	size_t bufsize;
 	int r;
-	u8 line[10240];
+	char line[10240];
 	
 	SC_FUNC_CALLED(card->ctx, 1);
 	sc_format_path("3F00", &path);
@@ -440,7 +440,7 @@ int sc_pkcs15_create_odf(struct sc_pkcs15_card *p15card)
 {
 	u8 *buf;
 	size_t buflen;
-	u8 line[10240];
+	char line[10240];
 	int r;
 	
 	r = encode_odf(p15card, &buf, &buflen);
diff --git a/src/tools/opensc-explorer.c b/src/tools/opensc-explorer.c
index 3b4a686a..eab2a034 100644
--- a/src/tools/opensc-explorer.c
+++ b/src/tools/opensc-explorer.c
@@ -380,11 +380,12 @@ int do_create(const char *arg, const char *arg2)
 {
 	struct sc_path path;
 	struct sc_file file;
-	size_t size;
+	int size;
 	int i, r;
 
 	if (arg_to_path(arg, &path) != 0)
 		goto usage;
+	/* %z isn't supported everywhere */
 	if (sscanf(arg2, "%d", &size) != 1)
 		goto usage;
 	memset(&file, 0, sizeof(file));
@@ -393,7 +394,7 @@ int do_create(const char *arg, const char *arg2)
 	file.ef_structure = SC_FILE_EF_TRANSPARENT;
 	for (i = 0; i < SC_MAX_AC_OPS; i++)
 		file.acl[i] = SC_AC_NONE;
-	file.size = size;
+	file.size = (size_t) size;
 	file.status = SC_FILE_STATUS_ACTIVATED;
 	
 	r = sc_create_file(card, &file);
@@ -506,8 +507,8 @@ int do_get(const char *arg, const char *arg2)
 	if (strlen(arg2))
 		filename = arg2;
 	else {
-		sprintf(buf, "%02X%02X", path.value[0], path.value[1]);
-		filename = buf;
+		sprintf((char *) buf, "%02X%02X", path.value[0], path.value[1]);
+		filename = (char *) buf;
 	}
 	outf = fopen(filename, "w");
 	if (outf == NULL) {
@@ -569,8 +570,8 @@ int do_put(const char *arg, const char *arg2)
 	if (strlen(arg2))
 		filename = arg2;
 	else {
-		sprintf(buf, "%02X%02X", path.value[0], path.value[1]);
-		filename = buf;
+		sprintf((char *) buf, "%02X%02X", path.value[0], path.value[1]);
+		filename = (char *) buf;
 	}
 	outf = fopen(filename, "r");
 	if (outf == NULL) {