diff --git a/etc/opensc.conf.in b/etc/opensc.conf.in
index e84f8f0f..645be28a 100644
--- a/etc/opensc.conf.in
+++ b/etc/opensc.conf.in
@@ -300,6 +300,12 @@ app default {
 # Parameters for the OpenSC PKCS11 module
 app opensc-pkcs11 {
 	pkcs11 {
+		# Should the module work in PKCS#11 v2.20 (instead of v2.11) mode?
+		# This affects slot changes and PC/SC PnP, as v2.11 applications
+		# are not allowed to change the length of the slot list.
+		# Default: false
+		# v2_20_mode = true;
+
 		# Maximum Number of virtual slots.
 		# If there are more slots than defined here,
 		# the remaining slots will be hidden from PKCS#11.
diff --git a/src/pkcs11/framework-pkcs15.c b/src/pkcs11/framework-pkcs15.c
index e081ecbe..c40055aa 100644
--- a/src/pkcs11/framework-pkcs15.c
+++ b/src/pkcs11/framework-pkcs15.c
@@ -212,9 +212,9 @@ static void pkcs15_init_token_info(struct sc_pkcs15_card *card, CK_TOKEN_INFO_PT
 	pToken->ulFreePublicMemory = CK_UNAVAILABLE_INFORMATION;
 	pToken->ulTotalPrivateMemory = CK_UNAVAILABLE_INFORMATION;
 	pToken->ulFreePrivateMemory = CK_UNAVAILABLE_INFORMATION;
-	pToken->hardwareVersion.major = 1;
+	pToken->hardwareVersion.major = 0;
 	pToken->hardwareVersion.minor = 0;
-	pToken->firmwareVersion.major = 1;
+	pToken->firmwareVersion.major = 0;
 	pToken->firmwareVersion.minor = 0;
 }
 
diff --git a/src/pkcs11/framework-pkcs15init.c b/src/pkcs11/framework-pkcs15init.c
index d5b74808..ac071bd9 100644
--- a/src/pkcs11/framework-pkcs15init.c
+++ b/src/pkcs11/framework-pkcs15init.c
@@ -82,9 +82,9 @@ static CK_RV pkcs15init_create_tokens(struct sc_pkcs11_card *p11card)
 		pToken->ulFreePublicMemory = CK_UNAVAILABLE_INFORMATION;
 		pToken->ulTotalPrivateMemory = CK_UNAVAILABLE_INFORMATION;
 		pToken->ulFreePrivateMemory = CK_UNAVAILABLE_INFORMATION;
-		pToken->hardwareVersion.major = 1;
+		pToken->hardwareVersion.major = 0;
 		pToken->hardwareVersion.minor = 0;
-		pToken->firmwareVersion.major = 1;
+		pToken->firmwareVersion.major = 0;
 		pToken->firmwareVersion.minor = 0;
 	}
 
diff --git a/src/pkcs11/misc.c b/src/pkcs11/misc.c
index ba6d1af8..c5da7e3c 100644
--- a/src/pkcs11/misc.c
+++ b/src/pkcs11/misc.c
@@ -317,6 +317,7 @@ void load_pkcs11_parameters(struct sc_pkcs11_config *conf, sc_context_t *ctx)
 	int i;
 	
 	/* Set defaults */
+	conf->v2_20_mode = 0;
 	conf->max_virtual_slots = 16;
 	conf->slots_per_card = 4;
 	conf->hide_empty_tokens = 0;
@@ -330,6 +331,7 @@ void load_pkcs11_parameters(struct sc_pkcs11_config *conf, sc_context_t *ctx)
 		return;
 
 	/* contains the defaults, if there is a "pkcs11" config block */
+	conf->v2_20_mode = scconf_get_bool(conf_block, "v2_20_mode", conf->v2_20_mode);
 	conf->max_virtual_slots = scconf_get_int(conf_block, "max_virtual_slots", conf->max_virtual_slots);
 	/*XXX: rename the option in 0.12+ */
 	conf->slots_per_card = scconf_get_int(conf_block, "num_slots", conf->slots_per_card);
diff --git a/src/pkcs11/pkcs11-global.c b/src/pkcs11/pkcs11-global.c
index 36ca21be..55c4c875 100644
--- a/src/pkcs11/pkcs11-global.c
+++ b/src/pkcs11/pkcs11-global.c
@@ -295,15 +295,15 @@ CK_RV C_GetInfo(CK_INFO_PTR pInfo)
 
 	memset(pInfo, 0, sizeof(CK_INFO));
 	pInfo->cryptokiVersion.major = 2;
-	pInfo->cryptokiVersion.minor = 11;
+	pInfo->cryptokiVersion.minor = sc_pkcs11_conf.v2_20_mode ? 20 : 11;
 	strcpy_bp(pInfo->manufacturerID,
 		  "OpenSC (www.opensc-project.org)",
 		  sizeof(pInfo->manufacturerID));
 	strcpy_bp(pInfo->libraryDescription,
 		  "smart card PKCS#11 API",
 		  sizeof(pInfo->libraryDescription));
-	pInfo->libraryVersion.major = 1;
-	pInfo->libraryVersion.minor = 0;
+	pInfo->libraryVersion.major = 0;
+	pInfo->libraryVersion.minor = 0; /* FIXME: use 0.116 for 0.11.6 from autoconf */
 
 out:	sc_pkcs11_unlock();
 	return rv;
@@ -347,7 +347,8 @@ CK_RV C_GetSlotList(CK_BBOOL       tokenPresent,  /* only slots with token prese
 	}
 
 	sc_debug(context, "Getting slot listing\n");
-	if (pSlotList == NULL_PTR) {
+	/* Slot list can only change in v2.20 */
+	if (pSlotList == NULL_PTR && sc_pkcs11_conf.v2_20_mode) {
 		sc_ctx_detect_readers(context);
 	}
 	card_detect_all();
@@ -684,7 +685,7 @@ sc_pkcs11_init_lock(CK_C_INITIALIZE_ARGS_PTR args)
 		/* Shall be used in threaded envirnoment, must use app provided locking */
 		global_locking = args;
 	} else if (!applock && !oslock) {
-		/* Shall not be used in threaded environemtn, use operating system locking */
+		/* Shall not be used in threaded environment, use operating system locking */
 		global_locking = default_mutex_funcs;
 	}
 
@@ -753,7 +754,7 @@ void sc_pkcs11_free_lock(void)
 }
 
 CK_FUNCTION_LIST pkcs11_function_list = {
-	{ 2, 11 },
+	{ 2, 11 }, /* Note: NSS/Firefox ignores this version number and uses C_GetInfo() */
 	C_Initialize,
 	C_Finalize,
 	C_GetInfo,
diff --git a/src/pkcs11/sc-pkcs11.h b/src/pkcs11/sc-pkcs11.h
index ddd7498b..6751484a 100644
--- a/src/pkcs11/sc-pkcs11.h
+++ b/src/pkcs11/sc-pkcs11.h
@@ -87,6 +87,7 @@ struct sc_pkcs11_pool {
 };
 
 struct sc_pkcs11_config {
+	unsigned int v2_20_mode;
 	unsigned int max_virtual_slots;
 	unsigned int slots_per_card;
 	unsigned char hide_empty_tokens;