diff --git a/src/libopensc/errors.c b/src/libopensc/errors.c
index 33bbf0a3..06942016 100644
--- a/src/libopensc/errors.c
+++ b/src/libopensc/errors.c
@@ -31,8 +31,8 @@ const char *sc_strerror(int error)
 	const char *rdr_errors[] = {
 		"Generic reader error",
 		"No readers found",
-		"Slot not found", /* Not used */
-		"Slot already connected", /* Not used */
+		"UNUSED",
+		"UNUSED",
 		"Card not present",
 		"Card removed",
 		"Card reset",
@@ -40,7 +40,7 @@ const char *sc_strerror(int error)
 		"Timed out while waiting for user input",
 		"Input operation cancelled by user",
 		"The two PINs did not match",
-		"Message too long (keypad)", /* Not used */
+		"Message too long (keypad)",
 		"Timeout while waiting for event from card reader",
 		"Unresponsive card (correctly inserted?)",
 		"Reader detached (hotplug device?)",
@@ -71,8 +71,8 @@ const char *sc_strerror(int error)
 	const int card_base = -SC_ERROR_CARD_CMD_FAILED;
 	const char *arg_errors[] = {
 		"Invalid arguments",
-		"Command too short",
-		"Command too long",
+		"UNUSED",
+		"UNUSED",
 		"Buffer too small",
 		"Invalid PIN length",
 		"Invalid data",
@@ -99,14 +99,14 @@ const char *sc_strerror(int error)
 	};
 	const int int_base = -SC_ERROR_INTERNAL;
 	const char *p15i_errors[] = {
-		"Generic PKCS #15 initialization error",
+		"Generic PKCS#15 initialization error",
 		"Syntax error",
-		"Inconsistent or incomplete pkcs15 profile",
+		"Inconsistent or incomplete PKCS#15 profile",
 		"Key length/algorithm not supported by card",
 		"No default (transport) key available",
-		"The PKCS#15 Key/certificate ID specified is not unique",
+		"UNUSED",
 		"Unable to load key and certificate(s) from file",
-		"Object is not compatible with intended use",
+		"UNUSED",
 		"File template not found",
 		"Invalid PIN reference",
 		"File too small",
diff --git a/src/libopensc/errors.h b/src/libopensc/errors.h
index 1fa31470..39018e54 100644
--- a/src/libopensc/errors.h
+++ b/src/libopensc/errors.h
@@ -31,8 +31,8 @@ extern "C" {
 /* Errors related to reader operation */
 #define SC_ERROR_READER				-1100
 #define SC_ERROR_NO_READERS_FOUND		-1101
-#define SC_ERROR_SLOT_NOT_FOUND			-1102 /* FIXME: not used */
-#define SC_ERROR_SLOT_ALREADY_CONNECTED		-1103 /* FIXME: not used */
+/* Unused: -1102 */
+/* Unused: -1103 */
 #define SC_ERROR_CARD_NOT_PRESENT		-1104
 #define SC_ERROR_CARD_REMOVED			-1105
 #define SC_ERROR_CARD_RESET			-1106
@@ -40,7 +40,7 @@ extern "C" {
 #define SC_ERROR_KEYPAD_TIMEOUT			-1108
 #define SC_ERROR_KEYPAD_CANCELLED		-1109
 #define SC_ERROR_KEYPAD_PIN_MISMATCH		-1110
-#define SC_ERROR_KEYPAD_MSG_TOO_LONG		-1111 /* FIXME: not used */
+#define SC_ERROR_KEYPAD_MSG_TOO_LONG		-1111
 #define SC_ERROR_EVENT_TIMEOUT			-1112
 #define SC_ERROR_CARD_UNRESPONSIVE		-1113
 #define SC_ERROR_READER_DETACHED		-1114
@@ -69,8 +69,8 @@ extern "C" {
 
 /* Returned by OpenSC library when called with invalid arguments */
 #define SC_ERROR_INVALID_ARGUMENTS		-1300
-#define SC_ERROR_CMD_TOO_SHORT			-1301
-#define SC_ERROR_CMD_TOO_LONG			-1302
+/* Unused: -1301 */
+/* Unused: -1302 */
 #define SC_ERROR_BUFFER_TOO_SMALL		-1303
 #define SC_ERROR_INVALID_PIN_LENGTH		-1304
 #define SC_ERROR_INVALID_DATA			-1305
@@ -100,12 +100,12 @@ extern "C" {
 #define SC_ERROR_INCONSISTENT_PROFILE		-1502
 #define SC_ERROR_INCOMPATIBLE_KEY		-1503
 #define SC_ERROR_NO_DEFAULT_KEY			-1504
-#define SC_ERROR_ID_NOT_UNIQUE			-1505
-#define SC_ERROR_CANNOT_LOAD_KEY		-1006
-#define SC_ERROR_INCOMPATIBLE_OBJECT		-1007
-#define SC_ERROR_TEMPLATE_NOT_FOUND		-1008
-#define SC_ERROR_INVALID_PIN_REFERENCE		-1009
-#define SC_ERROR_FILE_TOO_SMALL			-1010
+/* Unused: -1505 */
+#define SC_ERROR_CANNOT_LOAD_KEY		-1506
+/* Unused: -1007 */
+#define SC_ERROR_TEMPLATE_NOT_FOUND		-1508
+#define SC_ERROR_INVALID_PIN_REFERENCE		-1509
+#define SC_ERROR_FILE_TOO_SMALL			-1510
 
 /* Errors that do not fit the categories above */
 #define SC_ERROR_UNKNOWN			-1900