diff --git a/src/ac/ac_soap.c b/src/ac/ac_soap.c
index 5dec364..25ce4f2 100644
--- a/src/ac/ac_soap.c
+++ b/src/ac/ac_soap.c
@@ -502,7 +502,7 @@ void ac_soapclient_free_request(struct ac_soap_request* request)  {
 }
 
 /* */
-int ac_soapclient_add_param(struct ac_soap_request* request, char* type, char* name, char* value) {
+int ac_soapclient_add_param(struct ac_soap_request* request, const char* type, const char* name, const char* value) {
 	xmlNodePtr xmlParam;
 
 	ASSERT(request != NULL);
diff --git a/src/ac/ac_soap.h b/src/ac/ac_soap.h
index 2e331d5..2a1eb42 100644
--- a/src/ac/ac_soap.h
+++ b/src/ac/ac_soap.h
@@ -86,7 +86,7 @@ void ac_soapclient_free_server(struct ac_http_soap_server* server);
 
 /* Request */
 struct ac_soap_request* ac_soapclient_create_request(char* method, char* urinamespace);
-int ac_soapclient_add_param(struct ac_soap_request* request, char* type, char* name, char* value);
+int ac_soapclient_add_param(struct ac_soap_request* request, const char* type, const char* name, const char* value);
 char* ac_soapclient_get_request(struct ac_soap_request* request);
 void ac_soapclient_free_request(struct ac_soap_request* request);