diff --git a/common/utils/oai_asn1.h b/common/utils/oai_asn1.h
index 60a5b39ac5..f55150d17f 100644
--- a/common/utils/oai_asn1.h
+++ b/common/utils/oai_asn1.h
@@ -32,7 +32,7 @@
  *\param[in] pointer to the BIT_STRING_t object.
  *\return the extracted value.
  */
-static inline uint8_t BIT_STRING_to_uint8(BIT_STRING_t *asn) {
+static inline uint8_t BIT_STRING_to_uint8(const BIT_STRING_t *asn) {
   DevCheck ((asn->size == 1), asn->size, 0, 0);
 
   return asn->buf[0] >> asn->bits_unused;
@@ -43,7 +43,7 @@ static inline uint8_t BIT_STRING_to_uint8(BIT_STRING_t *asn) {
  *\param[in] pointer to the BIT_STRING_t object.
  *\return the extracted value.
  */
-static inline uint16_t BIT_STRING_to_uint16(BIT_STRING_t *asn) {
+static inline uint16_t BIT_STRING_to_uint16(const BIT_STRING_t *asn) {
   uint16_t result = 0;
   int index = 0;
 
@@ -69,7 +69,7 @@ static inline uint16_t BIT_STRING_to_uint16(BIT_STRING_t *asn) {
  *\param[in] pointer to the BIT_STRING_t object.
  *\return the extracted value.
  */
-static inline uint32_t BIT_STRING_to_uint32(BIT_STRING_t *asn) {
+static inline uint32_t BIT_STRING_to_uint32(const BIT_STRING_t *asn) {
   uint32_t result = 0;
   size_t index;
 
@@ -91,7 +91,7 @@ static inline uint32_t BIT_STRING_to_uint32(BIT_STRING_t *asn) {
  *\param[in] pointer to the BIT_STRING_t object.
  *\return the extracted value.
  */
-static inline uint64_t BIT_STRING_to_uint64(BIT_STRING_t *asn) {
+static inline uint64_t BIT_STRING_to_uint64(const BIT_STRING_t *asn) {
   uint64_t result = 0;
   size_t index;
   int shift;