diff --git a/src/agent.c b/src/agent.c
index 09af91c7..fa52b647 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -491,7 +491,7 @@ int agent_set_remote_description(juice_agent_t *agent, const char *sdp) {
 			return 0;
 		}
 
-		JLOG_WARN("ICE restart is unsupported");
+		JLOG_WARN("ICE restart is not supported");
 		conn_unlock(agent);
 		return -1;
 	}
@@ -560,9 +560,26 @@ int agent_add_remote_candidate(juice_agent_t *agent, const char *sdp) {
 	return ret;
 }
 
+int agent_set_local_ice_attributes(juice_agent_t *agent, const char *ufrag, const char *pwd)
+{
+	if (agent->conn_impl) {
+		JLOG_WARN("Unable to set ICE attributes, candidates gathering already started");
+		return JUICE_ERR_FAILED;
+	}
+
+	if (strlen(ufrag) < 4 || strlen(pwd) < 22 || !ice_is_valid_string(ufrag) || !ice_is_valid_string(pwd)) {
+		JLOG_WARN("Invalid ICE attributes");
+		return JUICE_ERR_INVALID;
+	}
+
+	snprintf(agent->local.ice_ufrag, sizeof(agent->local.ice_ufrag), "%s", ufrag);
+	snprintf(agent->local.ice_pwd, sizeof(agent->local.ice_pwd), "%s", pwd);
+	return JUICE_ERR_SUCCESS;
+}
+
 int agent_add_turn_server(juice_agent_t *agent, const juice_turn_server_t *turn_server) {
 	if (agent->conn_impl) {
-		JLOG_WARN("Candidates gathering already started");
+		JLOG_WARN("Unable to add TURN server, candidates gathering already started");
 		return -1;
 	}
 
diff --git a/src/agent.h b/src/agent.h
index 0eb5b922..179e9983 100644
--- a/src/agent.h
+++ b/src/agent.h
@@ -158,6 +158,7 @@ int agent_resolve_servers(juice_agent_t *agent);
 int agent_get_local_description(juice_agent_t *agent, char *buffer, size_t size);
 int agent_set_remote_description(juice_agent_t *agent, const char *sdp);
 int agent_add_remote_candidate(juice_agent_t *agent, const char *sdp);
+int agent_set_local_ice_attributes(juice_agent_t *agent, const char *ufrag, const char *pwd);
 int agent_add_turn_server(juice_agent_t *agent, const juice_turn_server_t *turn_server);
 int agent_set_remote_gathering_done(juice_agent_t *agent);
 int agent_send(juice_agent_t *agent, const char *data, size_t size, int ds);
diff --git a/src/ice.c b/src/ice.c
index 393caeff..8961c1f1 100644
--- a/src/ice.c
+++ b/src/ice.c
@@ -110,7 +110,7 @@ int ice_parse_sdp(const char *sdp, ice_description_t *description) {
 		if (*sdp == '\n') {
 			if (size) {
 				buffer[size++] = '\0';
-				if(parse_sdp_line(buffer, description) == ICE_PARSE_ERROR)
+				if (parse_sdp_line(buffer, description) == ICE_PARSE_ERROR)
 					return ICE_PARSE_ERROR;
 
 				size = 0;
@@ -415,3 +415,14 @@ uint32_t ice_compute_priority(ice_candidate_type_t type, int family, int compone
 	p += 256 - CLAMP(component, 1, 256);
 	return p;
 }
+
+bool ice_is_valid_string(const char *str) {
+	if (!str)
+		return false;
+
+	for (size_t i = 0; i < strlen(str); ++i)
+		if (!isalpha(str[i]) && !isdigit(str[i]) && str[i] != '+' && str[i] != '/')
+			return false;
+
+	return true;
+}
diff --git a/src/ice.h b/src/ice.h
index 51078bd4..86f1de3a 100644
--- a/src/ice.h
+++ b/src/ice.h
@@ -101,4 +101,6 @@ int ice_candidates_count(const ice_description_t *description, ice_candidate_typ
 
 uint32_t ice_compute_priority(ice_candidate_type_t type, int family, int component, int index);
 
+bool ice_is_valid_string(const char *str);
+
 #endif
diff --git a/src/juice.c b/src/juice.c
index 62647813..d7c79139 100644
--- a/src/juice.c
+++ b/src/juice.c
@@ -150,20 +150,10 @@ JUICE_EXPORT int juice_get_selected_addresses(juice_agent_t *agent, char *local,
 
 int juice_set_local_ice_attributes(juice_agent_t *agent, const char *ufrag, const char *pwd)
 {
-	if (agent->conn_impl) {
-		JLOG_WARN("Candidates gathering already started");
-		return JUICE_ERR_FAILED;
-	}
-
-	if (!ufrag || !pwd || strlen(ufrag) < 4 || strlen(pwd) < 22) {
-		JLOG_WARN("Invalid ICE credentials");
+	if (!ufrag || !pwd)
 		return JUICE_ERR_INVALID;
-	}
-
-	snprintf(agent->local.ice_ufrag, sizeof(agent->local.ice_ufrag), "%s", ufrag);
-	snprintf(agent->local.ice_pwd, sizeof(agent->local.ice_pwd), "%s", pwd);
 
-	return JUICE_ERR_SUCCESS;
+	return agent_set_local_ice_attributes(agent, ufrag, pwd);
 }
 
 JUICE_EXPORT const char *juice_state_to_string(juice_state_t state) {
diff --git a/test/ufrag.c b/test/ufrag.c
index c9d5de81..36ad9f72 100644
--- a/test/ufrag.c
+++ b/test/ufrag.c
@@ -41,6 +41,11 @@ int test_ufrag() {
 	if (juice_set_local_ice_attributes(agent, "usr", "pw01234567890123456789") != JUICE_ERR_INVALID)
 		success = false;
 
+	if (juice_set_local_ice_attributes(agent, "ufrag:", "pw01234567890123456789") != JUICE_ERR_INVALID)
+		success = false;
+
+	if (juice_set_local_ice_attributes(agent, "ufrag", "pw0123456789012345678?") != JUICE_ERR_INVALID)
+		success = false;
 
 	// Set local ICE attributes
 	juice_set_local_ice_attributes(agent, "ufrag", "pw01234567890123456789");