diff --git a/include/rjp.h b/include/rjp.h
index 303197c..ae85333 100644
--- a/include/rjp.h
+++ b/include/rjp.h
@@ -148,7 +148,7 @@ size_t rjp_num_members(const RJP_value* object);
 //Return the object member's key name
 char* rjp_member_name(const RJP_value* member);
 //Return the object member's key name length excluding null terminator
-size_t rjp_member_name_length(RJP_value* member);
+size_t rjp_member_name_length(const RJP_value* member);
 //Search for an object member with given key
 RJP_search_res rjp_search_member(const RJP_value* object, const char* search, size_t skip);
 //Search for first occurance of multiple keys. Returns first occurance of each.
diff --git a/src/rjp.c b/src/rjp.c
index 928c50c..1cf53a8 100644
--- a/src/rjp.c
+++ b/src/rjp.c
@@ -143,7 +143,7 @@ size_t rjp_num_members(const RJP_value* object){
 char* rjp_member_name(const RJP_value* member){
 	return ((RJP_object_member*)member)->name.value;
 }
-size_t rjp_member_name_length(RJP_value* member){
+size_t rjp_member_name_length(const RJP_value* member){
  return ((RJP_object_member*)member)->name.length;
 }