diff --git a/src/ifcparse/IfcSchema.h b/src/ifcparse/IfcSchema.h
index 158dcd1547..5f49eb6c7e 100644
--- a/src/ifcparse/IfcSchema.h
+++ b/src/ifcparse/IfcSchema.h
@@ -243,7 +243,7 @@ namespace IfcParse {
 
 		std::vector<const inverse_attribute*> inverse_attributes_;
 
-		class attribute_by_name_cmp : public std::unary_function<const attribute*, bool> {
+		class attribute_by_name_cmp {
 		private:
 			std::string name_;
 		public:
@@ -399,14 +399,14 @@ namespace IfcParse {
 		std::vector<const enumeration_type*> enumeration_types_;
 		std::vector<const entity*> entities_;
 
-		class declaration_by_name_cmp : public std::binary_function<const declaration*, const std::string&, bool> {
+		class declaration_by_name_cmp {
 		public:
 			bool operator()(const declaration* decl, const std::string& name) {
 				return decl->name_lc() < name;
 			}
 		};
 
-		class declaration_by_index_sort : public std::binary_function<const declaration*, const declaration*, bool> {
+		class declaration_by_index_sort  {
 		public:
 			bool operator()(const declaration* a, const declaration* b) {
 				return a->index_in_schema() < b->index_in_schema();