diff --git a/include/belle-sip/auth-helper.h b/include/belle-sip/auth-helper.h
index 937a3e6a8b336cd28c2c48aa790ef8f01e737e78..b6be8641fa831330d5435a6aa4587b4071211ccd 100644
--- a/include/belle-sip/auth-helper.h
+++ b/include/belle-sip/auth-helper.h
@@ -22,6 +22,9 @@
 #include "belle-sip/defs.h"
 #include "belle-sip/belle-sip.h"
 
+#define MAX_LENGTH_BYTE 32
+#define MAX_RESPONSE_SIZE 65
+
 BELLE_SIP_BEGIN_DECLS
 
 /**
diff --git a/src/auth_helper.c b/src/auth_helper.c
index 1b7946c56811d2c00288b28db0bb2875eb891943..7c5ea5f782c500b0d186a7c65cd6e4fd12411f9c 100644
--- a/src/auth_helper.c
+++ b/src/auth_helper.c
@@ -22,7 +22,6 @@
 #include <string.h>
 #include "bctoolbox/crypto.h"
 
-
 #ifndef BELLE_SIP_CNONCE_LENGTH
 #define BELLE_SIP_CNONCE_LENGTH 16
 #endif
@@ -100,7 +99,7 @@ int belle_sip_auth_helper_compute_ha1_for_algorithm(const char *userid, const ch
 		return -1;
 	}
 	size_t length_byte = (size - 1) / 2;
-	uint8_t out[32];
+	uint8_t out[MAX_LENGTH_BYTE];
 	size_t di;
 	char *ask;
 	if (!userid) {
@@ -138,7 +137,7 @@ int belle_sip_auth_helper_compute_ha2_for_algorithm(const char *method, const ch
 		return -1;
 	}
 	size_t length_byte = (size - 1) / 2;
-	uint8_t out[32];
+	uint8_t out[MAX_LENGTH_BYTE];
 	size_t di;
 	char *ask;
 	ha2[length_byte * 2] = '\0';
@@ -165,7 +164,7 @@ int belle_sip_auth_helper_compute_response_for_algorithm(const char *ha1, const
 		return -1;
 	}
 	size_t length_byte = (size - 1) / 2;
-	uint8_t out[32];
+	uint8_t out[MAX_LENGTH_BYTE];
 	size_t di;
 	char *ask;
 	response[length_byte * 2] = '\0';
@@ -200,7 +199,7 @@ int belle_sip_auth_helper_compute_response_qop_auth_for_algorithm(const char* ha
 		return -1;
 	}
 	size_t length_byte = (size - 1) / 2;
-	uint8_t out[32];
+	uint8_t out[MAX_LENGTH_BYTE];
 	size_t di;
 	char *ask;
 	char nounce_count_as_string[9];
@@ -240,8 +239,8 @@ int belle_sip_auth_helper_fill_authorization(belle_sip_header_authorization_t* a
 	}	
 	int auth_mode=0;
 	char* uri;
-	char ha2[65];
-	char response[65];
+	char ha2[MAX_RESPONSE_SIZE];
+	char response[MAX_RESPONSE_SIZE];
 	char cnonce[BELLE_SIP_CNONCE_LENGTH + 1];
 
 	response[size-1]=ha2[size-1]='\0';
diff --git a/tester/belle_sip_refresher_tester.c b/tester/belle_sip_refresher_tester.c
index f094eaa643581e70c13748170922183ccf7dac58..4f90145cb2dd7d96405ae488405b0546be59ab19 100644
--- a/tester/belle_sip_refresher_tester.c
+++ b/tester/belle_sip_refresher_tester.c
@@ -120,7 +120,7 @@ static void compute_response(const char* username
 									,char* response
                                     ,size_t size
                                     ,const char* algo) {
-	char ha1[65],ha2[65];
+	char ha1[MAX_RESPONSE_SIZE],ha2[MAX_RESPONSE_SIZE];
 	belle_sip_auth_helper_compute_ha1_for_algorithm(username,realm,passwd,ha1,size,algo);
 	belle_sip_auth_helper_compute_ha2_for_algorithm(method,uri,ha2,size,algo);
 	belle_sip_auth_helper_compute_response_for_algorithm(ha1,nonce,ha2,response,size,algo);
@@ -138,7 +138,7 @@ static void compute_response_auth_qop(const char* username
                                         ,char* response
                                         ,size_t size
                                         ,const char* algo) {
-	char ha1[65],ha2[65];
+	char ha1[MAX_RESPONSE_SIZE],ha2[MAX_RESPONSE_SIZE];
 	belle_sip_auth_helper_compute_ha1_for_algorithm(username,realm,passwd,ha1,size,algo);
 	belle_sip_auth_helper_compute_ha2_for_algorithm(method,uri,ha2,size,algo);
 	belle_sip_auth_helper_compute_response_qop_auth_for_algorithm(ha1, nonce,nonce_count, cnonce,qop,ha2,response,size,algo);
@@ -206,7 +206,7 @@ static void server_process_request_event(void *obj, const belle_sip_request_even
 					belle_sip_error("Algorithm [%s] is not correct ", algo);
 					return;
 				}
-				char local_resp[65];
+				char local_resp[MAX_RESPONSE_SIZE];
 				if (qop && strcmp(qop, "auth") == 0) {
 					compute_response_auth_qop(belle_sip_header_authorization_get_username(authorization)
 					                          , belle_sip_header_authorization_get_realm(authorization)