diff --git a/src/libopensc/card-coolkey.c b/src/libopensc/card-coolkey.c
index ca587cc5..134b3ce2 100644
--- a/src/libopensc/card-coolkey.c
+++ b/src/libopensc/card-coolkey.c
@@ -1339,8 +1339,11 @@ static int coolkey_get_token_info(sc_card_t *card, sc_pkcs15_tokeninfo_t * token
 	serial_number = coolkey_cuid_to_string(&priv->cuid);
 
 	if (label && manufacturer_id && serial_number) {
+		free(token_info->label);
 		token_info->label = label;
+		free(token_info->manufacturer_id);
 		token_info->manufacturer_id = manufacturer_id;
+		free(token_info->serial_number);
 		token_info->serial_number = serial_number;
 		return SC_SUCCESS;
 	}
diff --git a/src/libopensc/internal.h b/src/libopensc/internal.h
index be8d138f..d41c2187 100644
--- a/src/libopensc/internal.h
+++ b/src/libopensc/internal.h
@@ -125,6 +125,15 @@ unsigned short lebytes2ushort(const u8 *buf);
  */
 unsigned long lebytes2ulong(const u8 *buf);
 
+/* Usable for setting string elements of token info, which
+ * are either initialized to NULL or we need to clean
+ * previous value.
+ *
+ * @param   strp   The pointer where to store string
+ * @param   value  The string to store (is strdupped)
+ */
+void set_string(char **strp, const char *value);
+
 #define BYTES4BITS(num)  (((num) + 7) / 8)    /* number of bytes necessary to hold 'num' bits */
 
 /* Returns an scconf_block entry with matching ATR/ATRmask to the ATR specified,
diff --git a/src/libopensc/pkcs15-actalis.c b/src/libopensc/pkcs15-actalis.c
index 201d40f8..8b87a628 100644
--- a/src/libopensc/pkcs15-actalis.c
+++ b/src/libopensc/pkcs15-actalis.c
@@ -36,6 +36,7 @@
 #include "common/compat_strlcpy.h"
 #include "libopensc/pkcs15.h"
 #include "libopensc/log.h"
+#include "libopensc/internal.h"
 
 static int (*set_security_env) (sc_card_t *, const sc_security_env_t *, int);
 
@@ -60,13 +61,6 @@ static int do_sign(sc_card_t * card, const u8 * in, size_t inlen, u8 * out,
 	return card->ops->decipher(card, in, inlen, out, outlen);
 }
 
-static void set_string(char **strp, const char *value)
-{
-	if (*strp)
-		free(*strp);
-	*strp = value ? strdup(value) : NULL;
-}
-
 #if 1
 /* XXX: temporary copy of the old pkcs15emu functions,
  *      to be removed */
diff --git a/src/libopensc/pkcs15-cac.c b/src/libopensc/pkcs15-cac.c
index e8c13d5f..ccb27994 100644
--- a/src/libopensc/pkcs15-cac.c
+++ b/src/libopensc/pkcs15-cac.c
@@ -122,8 +122,8 @@ static int sc_pkcs15emu_cac_init(sc_pkcs15_card_t *p15card)
 
 	/* could read this off card if needed */
 
-	p15card->tokeninfo->label = strdup(cac_get_name(card->type));
-	p15card->tokeninfo->manufacturer_id = strdup(MANU_ID);
+	set_string(&p15card->tokeninfo->label, cac_get_name(card->type));
+	set_string(&p15card->tokeninfo->manufacturer_id, MANU_ID);
 
 	/*
 	 * get serial number
@@ -131,10 +131,10 @@ static int sc_pkcs15emu_cac_init(sc_pkcs15_card_t *p15card)
 	r = sc_card_ctl(card, SC_CARDCTL_GET_SERIALNR, &serial);
 	if (r < 0) {
 		sc_log(card->ctx, "sc_card_ctl rc=%d",r);
-		p15card->tokeninfo->serial_number = strdup("00000000");
+		set_string(&p15card->tokeninfo->serial_number, "00000000");
 	} else {
 		sc_bin_to_hex(serial.value, serial.len, buf, sizeof(buf), 0);
-		p15card->tokeninfo->serial_number = strdup(buf);
+		set_string(&p15card->tokeninfo->serial_number, buf);
 	}
 
 	/* set pins */
diff --git a/src/libopensc/pkcs15-coolkey.c b/src/libopensc/pkcs15-coolkey.c
index 414ab2f2..373ec7a5 100644
--- a/src/libopensc/pkcs15-coolkey.c
+++ b/src/libopensc/pkcs15-coolkey.c
@@ -497,9 +497,9 @@ static int sc_pkcs15emu_coolkey_init(sc_pkcs15_card_t *p15card)
 	r = sc_card_ctl(card, SC_CARDCTL_COOLKEY_GET_TOKEN_INFO, p15card->tokeninfo);
 	if (r < 0) {
 		/* put some defaults in if we didn't succeed */
-		p15card->tokeninfo->label = strdup("Coolkey");
-		p15card->tokeninfo->manufacturer_id = strdup("Unknown");
-		p15card->tokeninfo->serial_number = strdup("00000000");
+		set_string(&p15card->tokeninfo->label, "Coolkey");
+		set_string(&p15card->tokeninfo->manufacturer_id, "Unknown");
+		set_string(&p15card->tokeninfo->serial_number, "00000000");
 	}
 
 	/* set pins */
diff --git a/src/libopensc/pkcs15-esteid.c b/src/libopensc/pkcs15-esteid.c
index 5688cfb0..991dadf5 100644
--- a/src/libopensc/pkcs15-esteid.c
+++ b/src/libopensc/pkcs15-esteid.c
@@ -45,8 +45,8 @@ sc_pkcs15emu_esteid_init (sc_pkcs15_card_t * p15card)
 	size_t field_length = 0, modulus_length = 0;
 	sc_path_t tmppath;
 
-	p15card->tokeninfo->label = strdup("ID-kaart");
-	p15card->tokeninfo->manufacturer_id = strdup("AS Sertifitseerimiskeskus");
+	set_string(&p15card->tokeninfo->label, "ID-kaart");
+	set_string(&p15card->tokeninfo->manufacturer_id, "AS Sertifitseerimiskeskus");
 
 	/* Select application directory */
 	sc_format_path ("3f00eeee5044", &tmppath);
@@ -57,7 +57,7 @@ sc_pkcs15emu_esteid_init (sc_pkcs15_card_t * p15card)
 	r = sc_read_record (card, SC_ESTEID_PD_DOCUMENT_NR, buff, sizeof(buff), SC_RECORD_BY_REC_NR);
 	LOG_TEST_RET(card->ctx, r, "read document number failed");
 	buff[MIN((size_t) r, (sizeof buff)-1)] = '\0';
-	p15card->tokeninfo->serial_number = strdup((const char *)buff);
+	set_string(&p15card->tokeninfo->serial_number, (const char *)buff);
 
 	p15card->tokeninfo->flags = SC_PKCS15_TOKEN_PRN_GENERATION
 				  | SC_PKCS15_TOKEN_EID_COMPLIANT
diff --git a/src/libopensc/pkcs15-esteid2018.c b/src/libopensc/pkcs15-esteid2018.c
index af87550a..3c58f089 100644
--- a/src/libopensc/pkcs15-esteid2018.c
+++ b/src/libopensc/pkcs15-esteid2018.c
@@ -33,12 +33,6 @@
 #include "opensc.h"
 #include "pkcs15.h"
 
-static void set_string(char **strp, const char *value) {
-	if (*strp)
-		free(*strp);
-	*strp = value ? strdup(value) : NULL;
-}
-
 static int sc_pkcs15emu_esteid2018_init(sc_pkcs15_card_t *p15card) {
 	sc_card_t *card = p15card->card;
 	u8 buff[11];
@@ -61,6 +55,7 @@ static int sc_pkcs15emu_esteid2018_init(sc_pkcs15_card_t *p15card) {
 	for (j = 0; j < taglen; j++)
 		if (!isalnum(tag[j]))
 			LOG_FUNC_RETURN(card->ctx, SC_ERROR_INTERNAL);
+	free(p15card->tokeninfo->serial_number);
 	p15card->tokeninfo->serial_number = malloc(taglen + 1);
 	if (!p15card->tokeninfo->serial_number)
 		LOG_FUNC_RETURN(card->ctx, SC_ERROR_OUT_OF_MEMORY);
diff --git a/src/libopensc/pkcs15-gemsafeGPK.c b/src/libopensc/pkcs15-gemsafeGPK.c
index 4b80daf2..ff52a2e3 100644
--- a/src/libopensc/pkcs15-gemsafeGPK.c
+++ b/src/libopensc/pkcs15-gemsafeGPK.c
@@ -219,8 +219,8 @@ static int sc_pkcs15emu_gemsafeGPK_init(sc_pkcs15_card_t *p15card)
 
 	/* could read this off card if needed */
 
-	p15card->tokeninfo->label = strdup("GemSAFE");
-	p15card->tokeninfo->manufacturer_id = strdup(MANU_ID);
+	set_string(&p15card->tokeninfo->label, "GemSAFE");
+	set_string(&p15card->tokeninfo->manufacturer_id, MANU_ID);
 	/* get serial number */
 	r = sc_card_ctl(card, SC_CARDCTL_GET_SERIALNR, &serial);
 	if (r != SC_SUCCESS)
@@ -228,7 +228,7 @@ static int sc_pkcs15emu_gemsafeGPK_init(sc_pkcs15_card_t *p15card)
 	r = sc_bin_to_hex(serial.value, serial.len, buf, sizeof(buf), 0);
 	if (r != SC_SUCCESS)
 		return SC_ERROR_INTERNAL;
-	p15card->tokeninfo->serial_number = strdup(buf);
+	set_string(&p15card->tokeninfo->serial_number, buf);
 
 	/* test if we have a gemsafe app df */
 	memset(&path, 0, sizeof(path));
diff --git a/src/libopensc/pkcs15-gids.c b/src/libopensc/pkcs15-gids.c
index 68e93ca8..5ab46ee0 100644
--- a/src/libopensc/pkcs15-gids.c
+++ b/src/libopensc/pkcs15-gids.c
@@ -127,6 +127,7 @@ static int sc_pkcs15emu_gids_init (sc_pkcs15_card_t * p15card)
 	r = sc_card_ctl(card, SC_CARDCTL_GET_SERIALNR, NULL);
 	LOG_TEST_RET(card->ctx, r, "unable to get the serial number. Uninitialized card ?");
 
+	free(p15card->tokeninfo->serial_number);
 	p15card->tokeninfo->serial_number = (char*) malloc(card->serialnr.len *2 +1);
 	if (!p15card->tokeninfo->serial_number) {
 		LOG_FUNC_RETURN(card->ctx, SC_ERROR_OUT_OF_MEMORY);
diff --git a/src/libopensc/pkcs15-idprime.c b/src/libopensc/pkcs15-idprime.c
index d8826969..219dfa8c 100644
--- a/src/libopensc/pkcs15-idprime.c
+++ b/src/libopensc/pkcs15-idprime.c
@@ -68,8 +68,8 @@ static int sc_pkcs15emu_idprime_init(sc_pkcs15_card_t *p15card)
 	SC_FUNC_CALLED(card->ctx, SC_LOG_DEBUG_VERBOSE);
 
 	/* could read this off card if needed */
-	p15card->tokeninfo->label = strdup("IDPrime");
-	p15card->tokeninfo->manufacturer_id = strdup("Gemalto");
+	set_string(&p15card->tokeninfo->label, "IDPrime");
+	set_string(&p15card->tokeninfo->manufacturer_id, "Gemalto");
 
 	/*
 	 * get serial number
@@ -78,10 +78,10 @@ static int sc_pkcs15emu_idprime_init(sc_pkcs15_card_t *p15card)
 	r = sc_card_ctl(card, SC_CARDCTL_GET_SERIALNR, &serial);
 	if (r < 0) {
 		sc_log(card->ctx, "sc_card_ctl rc=%d", r);
-		p15card->tokeninfo->serial_number = strdup("00000000");
+		set_string(&p15card->tokeninfo->serial_number, "00000000");
 	} else {
 		sc_bin_to_hex(serial.value, serial.len, buf, sizeof(buf), 0);
-		p15card->tokeninfo->serial_number = strdup(buf);
+		set_string(&p15card->tokeninfo->serial_number, buf);
 	}
 	/* set pin */
 	sc_log(card->ctx,  "IDPrime adding pin...");
diff --git a/src/libopensc/pkcs15-itacns.c b/src/libopensc/pkcs15-itacns.c
index 52118e9a..c30fe772 100644
--- a/src/libopensc/pkcs15-itacns.c
+++ b/src/libopensc/pkcs15-itacns.c
@@ -168,13 +168,6 @@ static const struct {
  * Utility functions
  */
 
-static void set_string(char **strp, const char *value)
-{
-	if (*strp)
-		free(*strp);
-	*strp = value ? strdup(value) : NULL;
-}
-
 static int loadFile(const sc_pkcs15_card_t *p15card, const sc_path_t *path,
 	u8 *buf, const size_t buflen)
 {
diff --git a/src/libopensc/pkcs15-jpki.c b/src/libopensc/pkcs15-jpki.c
index 7c420d71..ead719f3 100644
--- a/src/libopensc/pkcs15-jpki.c
+++ b/src/libopensc/pkcs15-jpki.c
@@ -42,10 +42,10 @@ sc_pkcs15emu_jpki_init(sc_pkcs15_card_t * p15card)
 
 	LOG_FUNC_CALLED(p15card->card->ctx);
 
-	p15card->tokeninfo->label = strdup("JPKI");
-	p15card->tokeninfo->manufacturer_id = strdup("JPKI");
+	set_string(&p15card->tokeninfo->label, "JPKI");
+	set_string(&p15card->tokeninfo->manufacturer_id, "JPKI");
 	/* set dummy until we found serial number */
-	p15card->tokeninfo->serial_number = strdup("00000000");
+	set_string(&p15card->tokeninfo->serial_number, "00000000");
 
 	/* Select application directory */
 	if (drvdata->selected != SELECT_JPKI_AP) {
diff --git a/src/libopensc/pkcs15-oberthur.c b/src/libopensc/pkcs15-oberthur.c
index 17720e75..ac762adc 100644
--- a/src/libopensc/pkcs15-oberthur.c
+++ b/src/libopensc/pkcs15-oberthur.c
@@ -357,8 +357,8 @@ sc_oberthur_parse_tokeninfo (struct sc_pkcs15_card *p15card,
 
 	flags = *(buff + 0x22) * 0x100 + *(buff + 0x23);
 
-	p15card->tokeninfo->label = strdup(label);
-	p15card->tokeninfo->manufacturer_id = strdup("Oberthur/OpenSC");
+	set_string(&p15card->tokeninfo->label, label);
+	set_string(&p15card->tokeninfo->manufacturer_id, "Oberthur/OpenSC");
 
 	if (flags & 0x01)
 		p15card->tokeninfo->flags |= SC_PKCS15_TOKEN_PRN_GENERATION;
@@ -919,7 +919,7 @@ sc_pkcs15emu_oberthur_init(struct sc_pkcs15_card * p15card)
 
 	SC_FUNC_CALLED(card->ctx, SC_LOG_DEBUG_VERBOSE);
 	sc_bin_to_hex(card->serialnr.value, card->serialnr.len, serial, sizeof(serial), 0);
-	p15card->tokeninfo->serial_number = strdup(serial);
+	set_string(&p15card->tokeninfo->serial_number, serial);
 
 	p15card->ops.parse_df = sc_awp_parse_df;
 	p15card->ops.clear = sc_awp_clear;
diff --git a/src/libopensc/pkcs15-openpgp.c b/src/libopensc/pkcs15-openpgp.c
index e775e3b4..0ca9a422 100644
--- a/src/libopensc/pkcs15-openpgp.c
+++ b/src/libopensc/pkcs15-openpgp.c
@@ -132,15 +132,6 @@ static const pgp_manuf_map_t manuf_map[] = {
 	{ 0, NULL }
 };
 
-
-static void
-set_string(char **strp, const char *value)
-{
-	if (*strp)
-		free(*strp);
-	*strp = value? strdup(value) : NULL;
-}
-
 /*
  * This function pretty much follows what find_tlv in the GNUpg
  * code does.
diff --git a/src/libopensc/pkcs15-piv.c b/src/libopensc/pkcs15-piv.c
index c0b873c7..3641372d 100644
--- a/src/libopensc/pkcs15-piv.c
+++ b/src/libopensc/pkcs15-piv.c
@@ -620,8 +620,8 @@ static int sc_pkcs15emu_piv_init(sc_pkcs15_card_t *p15card)
 	/* could read this off card if needed */
 
 	/* CSP does not like a - in the name */
-	p15card->tokeninfo->label = strdup("PIV_II");
-	p15card->tokeninfo->manufacturer_id = strdup(MANU_ID);
+	set_string(&p15card->tokeninfo->label, "PIV_II");
+	set_string(&p15card->tokeninfo->manufacturer_id, MANU_ID);
 
 	/*
 	 * get serial number 
@@ -633,10 +633,10 @@ static int sc_pkcs15emu_piv_init(sc_pkcs15_card_t *p15card)
 	r = sc_card_ctl(card, SC_CARDCTL_GET_SERIALNR, &serial);
 	if (r < 0) {
 		sc_log(card->ctx, "sc_card_ctl rc=%d",r);
-		p15card->tokeninfo->serial_number = strdup("00000000");
+		set_string(&p15card->tokeninfo->serial_number, "00000000");
 	} else {
 		sc_bin_to_hex(serial.value, serial.len, buf, sizeof(buf), 0);
-		p15card->tokeninfo->serial_number = strdup(buf);
+		set_string(&p15card->tokeninfo->serial_number, buf);
 	}
 	/* US gov issued PIVs have CHUID with a FASCN that does not start with 9999 */
 	if (serial.len == 25 && !(serial.value[0] == 0xD4 && serial.value[1] == 0xE7 && serial.value[2] == 0x39 && (serial.value[3] | 0x7F) == 0xFF)) {
diff --git a/src/libopensc/pkcs15-sc-hsm.c b/src/libopensc/pkcs15-sc-hsm.c
index 95560281..64a7b895 100644
--- a/src/libopensc/pkcs15-sc-hsm.c
+++ b/src/libopensc/pkcs15-sc-hsm.c
@@ -940,6 +940,7 @@ static int sc_pkcs15emu_sc_hsm_init (sc_pkcs15_card_t * p15card)
 	assert(len >= 8);
 	len -= 5;
 
+	free(p15card->tokeninfo->serial_number);
 	p15card->tokeninfo->serial_number = calloc(len + 1, 1);
 	if (p15card->tokeninfo->serial_number == NULL)
 		LOG_FUNC_RETURN(card->ctx, SC_ERROR_OUT_OF_MEMORY);
diff --git a/src/libopensc/pkcs15-tccardos.c b/src/libopensc/pkcs15-tccardos.c
index 67692230..dd8ad839 100644
--- a/src/libopensc/pkcs15-tccardos.c
+++ b/src/libopensc/pkcs15-tccardos.c
@@ -320,15 +320,11 @@ static int sc_pkcs15_tccardos_init_func(sc_pkcs15_card_t *p15card)
 	if (r != SC_SUCCESS)
 		return r;
 	/* set card label */
-	if (p15card->tokeninfo->label != NULL)
-		free(p15card->tokeninfo->label);
-	p15card->tokeninfo->label = strdup(TC_CARDOS_LABEL);
+	set_string(&p15card->tokeninfo->label, TC_CARDOS_LABEL);
 	if (p15card->tokeninfo->label == NULL)
 		return SC_ERROR_OUT_OF_MEMORY;
 	/* set the manufacturer ID */
-	if (p15card->tokeninfo->manufacturer_id != NULL)
-		free(p15card->tokeninfo->manufacturer_id);
-	p15card->tokeninfo->manufacturer_id = strdup(MANU_ID);
+	set_string(&p15card->tokeninfo->manufacturer_id, MANU_ID);
 	if (p15card->tokeninfo->manufacturer_id == NULL)
 		return SC_ERROR_OUT_OF_MEMORY;
 	/* set the serial number */
@@ -336,7 +332,7 @@ static int sc_pkcs15_tccardos_init_func(sc_pkcs15_card_t *p15card)
 	if (r != SC_SUCCESS || iccsn.len < 5+8)
 		return SC_ERROR_INTERNAL;
 	sc_bin_to_hex(iccsn.value + 5, 8, hex_buf, sizeof(hex_buf), 0);
-	p15card->tokeninfo->serial_number = strdup(hex_buf);
+	set_string(&p15card->tokeninfo->serial_number, hex_buf);
 	if (p15card->tokeninfo->serial_number == NULL)
 		return SC_ERROR_OUT_OF_MEMORY;
 	/* select the application DF */
diff --git a/src/libopensc/pkcs15-tcos.c b/src/libopensc/pkcs15-tcos.c
index be886ec0..57ce3515 100644
--- a/src/libopensc/pkcs15-tcos.c
+++ b/src/libopensc/pkcs15-tcos.c
@@ -287,8 +287,8 @@ static int detect_netkey(
 	sprintf(dir,"%04X", f->id);
 	sc_file_free(f);
 
-	p15card->tokeninfo->manufacturer_id = strdup("TeleSec GmbH");
-	p15card->tokeninfo->label = strdup(card->type==SC_CARD_TYPE_TCOS_V3 ? "NetKey V3 Card" : "NetKey Card");
+	set_string(&p15card->tokeninfo->manufacturer_id, "TeleSec GmbH");
+	set_string(&p15card->tokeninfo->label, card->type==SC_CARD_TYPE_TCOS_V3 ? "NetKey V3 Card" : "NetKey Card");
 	keylen= card->type==SC_CARD_TYPE_TCOS_V3 ? 2048 : 1024;
 	c_auth= card->type==SC_CARD_TYPE_TCOS_V3 ? "C500" : "C100";
 
@@ -375,8 +375,8 @@ static int detect_idkey(
 	memcpy(p.value, "\xD2\x76\x00\x00\x03\x0C\x01", p.len=7);
 	if (sc_select_file(card,&p,NULL)!=SC_SUCCESS) return 1;
 
-	p15card->tokeninfo->manufacturer_id = strdup("TeleSec GmbH");
-	p15card->tokeninfo->label = strdup("IDKey Card");
+	set_string(&p15card->tokeninfo->manufacturer_id, "TeleSec GmbH");
+	set_string(&p15card->tokeninfo->label, "IDKey Card");
 
 	insert_cert(p15card, "DF074331", 0x45, 1, "Signatur Zertifikat 1");
 	insert_cert(p15card, "DF074332", 0x46, 1, "Signatur Zertifikat 2");
@@ -407,8 +407,8 @@ static int detect_signtrust(
 	sc_pkcs15_card_t *p15card
 ){
 	if(insert_cert(p15card,"8000DF01C000", 0x45, 1, "Signatur Zertifikat")) return 1;
-	p15card->tokeninfo->manufacturer_id = strdup("Deutsche Post");
-	p15card->tokeninfo->label = strdup("SignTrust Card");
+	set_string(&p15card->tokeninfo->manufacturer_id, "Deutsche Post");
+	set_string(&p15card->tokeninfo->label, "SignTrust Card");
 
 	insert_cert(p15card,"800082008220", 0x46, 1, "Verschluesselungs Zertifikat");
 	insert_cert(p15card,"800083008320", 0x47, 1, "Authentifizierungs Zertifikat");
@@ -437,8 +437,8 @@ static int detect_datev(
 	sc_pkcs15_card_t *p15card
 ){
 	if(insert_cert(p15card,"3000C500", 0x45, 0, "Signatur Zertifikat")) return 1;
-	p15card->tokeninfo->manufacturer_id = strdup("DATEV");
-	p15card->tokeninfo->label = strdup("DATEV Classic");
+	set_string(&p15card->tokeninfo->manufacturer_id, "DATEV");
+	set_string(&p15card->tokeninfo->label, "DATEV Classic");
 
 	insert_cert(p15card,"DF02C200", 0x46, 0, "Verschluesselungs Zertifikat");
 	insert_cert(p15card,"DF02C500", 0x47, 0, "Authentifizierungs Zertifikat");
@@ -458,8 +458,8 @@ static int detect_unicard(
 	sc_pkcs15_card_t *p15card
 ){
 	if(!insert_cert(p15card,"41004352", 0x45, 1, "Zertifikat 1")){
-		p15card->tokeninfo->manufacturer_id = strdup("JLU Giessen");
-		p15card->tokeninfo->label = strdup("JLU Giessen Card");
+		set_string(&p15card->tokeninfo->manufacturer_id, "JLU Giessen");
+		set_string(&p15card->tokeninfo->label, "JLU Giessen Card");
 
 		insert_cert(p15card,"41004353", 0x46, 1, "Zertifikat 2");
 		insert_cert(p15card,"41004354", 0x47, 1, "Zertifikat 3");
@@ -468,8 +468,8 @@ static int detect_unicard(
 		insert_key(p15card,"41005105", 0x47, 0x85, 1024, 1, "Schluessel 3");
 
 	} else if(!insert_cert(p15card,"41014352", 0x45, 1, "Zertifikat 1")){
-		p15card->tokeninfo->manufacturer_id = strdup("TU Darmstadt");
-		p15card->tokeninfo->label = strdup("TUD Card");
+		set_string(&p15card->tokeninfo->manufacturer_id, "TU Darmstadt");
+		set_string(&p15card->tokeninfo->label, "TUD Card");
 
 		insert_cert(p15card,"41014353", 0x46, 1, "Zertifikat 2");
 		insert_cert(p15card,"41014354", 0x47, 1, "Zertifikat 3");
@@ -511,7 +511,7 @@ int sc_pkcs15emu_tcos_init_ex(
 	}
 	sc_bin_to_hex(serialnr.value, serialnr.len , serial, sizeof(serial), 0);
 	serial[19] = '\0';
-	p15card->tokeninfo->serial_number = strdup(serial);
+	set_string(&p15card->tokeninfo->serial_number, serial);
 
 	if(!detect_netkey(p15card)) return SC_SUCCESS;
 	if(!detect_idkey(p15card)) return SC_SUCCESS;
diff --git a/src/libopensc/pkcs15.c b/src/libopensc/pkcs15.c
index c58c34fd..704dd0a8 100644
--- a/src/libopensc/pkcs15.c
+++ b/src/libopensc/pkcs15.c
@@ -220,6 +220,7 @@ int sc_pkcs15_parse_tokeninfo(sc_context_t *ctx,
 	LOG_TEST_RET(ctx, r, "ASN.1 parsing of EF(TokenInfo) failed");
 
 	if (asn1_toki_attrs[1].flags & SC_ASN1_PRESENT && serial_len > 0)   {
+		free(ti->serial_number);
 		ti->serial_number = malloc(serial_len * 2 + 1);
 		if (ti->serial_number == NULL)
 			return SC_ERROR_OUT_OF_MEMORY;
@@ -732,18 +733,12 @@ sc_pkcs15_free_tokeninfo(struct sc_pkcs15_tokeninfo *tokeninfo)
 	if (!tokeninfo)
 		return;
 
-	if (tokeninfo->label != NULL)
-		free(tokeninfo->label);
-	if (tokeninfo->serial_number != NULL)
-		free(tokeninfo->serial_number);
-	if (tokeninfo->manufacturer_id != NULL)
-		free(tokeninfo->manufacturer_id);
-	if (tokeninfo->last_update.gtime != NULL)
-		free(tokeninfo->last_update.gtime);
-	if (tokeninfo->preferred_language != NULL)
-		free(tokeninfo->preferred_language);
-	if (tokeninfo->profile_indication.name != NULL)
-		free(tokeninfo->profile_indication.name);
+	free(tokeninfo->label);
+	free(tokeninfo->serial_number);
+	free(tokeninfo->manufacturer_id);
+	free(tokeninfo->last_update.gtime);
+	free(tokeninfo->preferred_language);
+	free(tokeninfo->profile_indication.name);
 	if (tokeninfo->seInfo != NULL) {
 		unsigned i;
 		for (i = 0; i < tokeninfo->num_seInfo; i++)
diff --git a/src/libopensc/sc.c b/src/libopensc/sc.c
index 1b957653..7541f6ec 100644
--- a/src/libopensc/sc.c
+++ b/src/libopensc/sc.c
@@ -237,6 +237,16 @@ unsigned long lebytes2ulong(const u8 *buf)
 		| (unsigned long)buf[0];
 }
 
+void set_string(char **strp, const char *value)
+{
+	if (strp == NULL) {
+		return;
+	}
+
+	free(*strp);
+	*strp = value ? strdup(value) : NULL;
+}
+
 void sc_init_oid(struct sc_object_id *oid)
 {
 	int ii;