diff --git a/src/tools/util.c b/src/tools/util.c
index 0a548755..0ad1fd9d 100644
--- a/src/tools/util.c
+++ b/src/tools/util.c
@@ -31,12 +31,28 @@
 #include <ctype.h>
 #include "util.h"
 
-int util_connect_card(sc_context_t *ctx, sc_card_t **cardp,
+int
+is_string_valid_atr(const char *atr_str)
+{
+	unsigned char atr[SC_MAX_ATR_SIZE];
+	size_t atr_len = sizeof(atr);
+
+	if (sc_hex_to_bin(atr_str, atr, &atr_len))
+		return 0;
+	if (atr_len < 2)
+		return 0;
+	if (atr[0] != 0x3B && atr[0] != 0x3F)
+		return 0;
+	return 1;
+}
+
+int
+util_connect_card(sc_context_t *ctx, sc_card_t **cardp,
 		 const char *reader_id, int do_wait, int verbose)
 {
-	sc_reader_t *reader, *found;
-	sc_card_t *card;
-	int r, tmp_reader_num;
+	struct sc_reader *reader = NULL, *found = NULL;
+	struct sc_card *card = NULL;
+	int r;
 
 	if (do_wait) {
 		unsigned int event;
@@ -61,11 +77,12 @@ int util_connect_card(sc_context_t *ctx, sc_card_t **cardp,
 			return 3;
 		}
 		reader = found;
-	} else {
-		if (sc_ctx_get_reader_count(ctx) == 0) {
-			fprintf(stderr, "No smart card readers found.\n");
-			return 1;
-		}
+	}
+	else if (sc_ctx_get_reader_count(ctx) == 0) {
+		fprintf(stderr, "No smart card readers found.\n");
+		return 1;
+	}
+	else   {
 		if (!reader_id) {
 			unsigned int i;
 			/* Automatically try to skip to a reader with a card if reader not specified */
@@ -78,35 +95,47 @@ int util_connect_card(sc_context_t *ctx, sc_card_t **cardp,
 			}
 			/* If no reader had a card, default to the first reader */
 			reader = sc_ctx_get_reader(ctx, 0);
-		} else {
-			/* If the reader identifiers looks like an ATR, try to find the reader with that card */
-			unsigned char atr_buf[SC_MAX_ATR_SIZE * 3];
-			size_t atr_buf_len = sizeof(atr_buf);
-			unsigned int i;
+		}
+		else {
+			/* If the reader identifier looks like an ATR, try to find the reader with that card */
+			if (is_string_valid_atr(reader_id))   {
+				unsigned char atr_buf[SC_MAX_ATR_SIZE * 3];
+				size_t atr_buf_len = sizeof(atr_buf);
+				unsigned int i;
 
-			if (sc_hex_to_bin(reader_id, atr_buf, &atr_buf_len) == SC_SUCCESS) {
+				sc_hex_to_bin(reader_id, atr_buf, &atr_buf_len);
 				/* Loop readers, looking for a card with ATR */
 				for (i = 0; i < sc_ctx_get_reader_count(ctx); i++) {
-					reader = sc_ctx_get_reader(ctx, i);
-					if ((sc_detect_card_presence(reader) & SC_READER_CARD_PRESENT) && (reader->atr.len > 0)) {
-						if (!memcmp(reader->atr.value, atr_buf, reader->atr.len)) {
-							fprintf(stderr, "Matched ATR in reader: %s\n", reader->name);
-							goto autofound;
-						}
-					}
+					struct sc_reader *rdr = sc_ctx_get_reader(ctx, i);
+
+					if (!(sc_detect_card_presence(rdr) & SC_READER_CARD_PRESENT))
+						continue;
+					else if (rdr->atr.len != atr_buf_len)
+						continue;
+					else if (memcmp(rdr->atr.value, atr_buf, rdr->atr.len))
+						continue;
+
+					fprintf(stderr, "Matched ATR in reader: %s\n", rdr->name);
+					reader = rdr;
+					goto autofound;
 				}
 			}
-			if (!sscanf(reader_id, "%d", &tmp_reader_num)) {
-				/* Try to get the reader by name if it does not parse as a number */
-				reader = sc_ctx_get_reader_by_name(ctx, reader_id);
-			} else {
-				reader = sc_ctx_get_reader(ctx, tmp_reader_num);
+			else   {
+				char *endptr = NULL;
+				unsigned int num;
+
+				errno = 0;
+				num = strtol(reader_id, &endptr, 0);
+				if (!errno && endptr && *endptr == '\0')
+					reader = sc_ctx_get_reader(ctx, num);
+				else
+					reader = sc_ctx_get_reader_by_name(ctx, reader_id);
 			}
 		}
 autofound:
 		if (!reader) {
-			fprintf(stderr,
-				"Reader \"%s\" not found (%d reader(s) detected)\n", reader_id, sc_ctx_get_reader_count(ctx));
+			fprintf(stderr, "Reader \"%s\" not found (%d reader(s) detected)\n",
+					reader_id, sc_ctx_get_reader_count(ctx));
 			return 1;
 		}
 
@@ -118,20 +147,18 @@ autofound:
 
 	if (verbose)
 		printf("Connecting to card in reader %s...\n", reader->name);
-	if ((r = sc_connect_card(reader, &card)) < 0) {
-		fprintf(stderr,
-			"Failed to connect to card: %s\n",
-			sc_strerror(r));
+	r = sc_connect_card(reader, &card);
+	if (r < 0) {
+		fprintf(stderr, "Failed to connect to card: %s\n", sc_strerror(r));
 		return 1;
 	}
 
 	if (verbose)
 		printf("Using card driver %s.\n", card->driver->name);
 
-	if ((r = sc_lock(card)) < 0) {
-		fprintf(stderr,
-			"Failed to lock card: %s\n",
-			sc_strerror(r));
+	r = sc_lock(card);
+	if (r < 0) {
+		fprintf(stderr, "Failed to lock card: %s\n", sc_strerror(r));
 		sc_disconnect_card(card);
 		return 1;
 	}