diff --git a/src/cpp/cpp_typecheck_conversions.cpp b/src/cpp/cpp_typecheck_conversions.cpp
index 8699ec1e99f..7549344b19c 100644
--- a/src/cpp/cpp_typecheck_conversions.cpp
+++ b/src/cpp/cpp_typecheck_conversions.cpp
@@ -480,12 +480,15 @@ bool cpp_typecheckt::standard_conversion_pointer(
     return true;
   }
 
-  if(type.find("to-member").is_not_nil())
+  if(type.find(ID_to_member).is_not_nil())
     return false;
 
-  if(expr.type().id() != ID_pointer ||
-     expr.type().find("to-member").is_not_nil())
+  if(
+    expr.type().id() != ID_pointer ||
+    expr.type().find(ID_to_member).is_not_nil())
+  {
     return false;
+  }
 
   typet sub_from=follow(expr.type().subtype());
   typet sub_to=follow(type.subtype());
@@ -559,13 +562,14 @@ bool cpp_typecheckt::standard_conversion_pointer_to_member(
   const typet &type,
   exprt &new_expr)
 {
-  if(type.id()!=ID_pointer ||
-     is_reference(type) ||
-     type.find("to-member").is_nil())
+  if(
+    type.id() != ID_pointer || is_reference(type) ||
+    type.find(ID_to_member).is_nil())
+  {
     return false;
+  }
 
-  if(expr.type().id() != ID_pointer ||
-     expr.type().find("to-member").is_nil())
+  if(expr.type().id() != ID_pointer || expr.type().find(ID_to_member).is_nil())
     return false;
 
   if(type.subtype()!=expr.type().subtype())
@@ -609,13 +613,11 @@ bool cpp_typecheckt::standard_conversion_pointer_to_member(
     return true;
   }
 
-  struct_typet from_struct =
-    to_struct_type(follow(static_cast<const typet &>
-      (expr.type().find("to-member"))));
+  struct_typet from_struct = to_struct_type(
+    follow(static_cast<const typet &>(expr.type().find(ID_to_member))));
 
   struct_typet to_struct =
-    to_struct_type(follow(static_cast<const typet &>
-      (type.find("to-member"))));
+    to_struct_type(follow(static_cast<const typet &>(type.find(ID_to_member))));
 
   if(subtype_typecast(to_struct, from_struct))
   {
@@ -1588,11 +1590,11 @@ bool cpp_typecheckt::cast_away_constness(
 
   if(is_reference(nt1))
     nt1.remove(ID_C_reference);
-  nt1.remove("to-member");
+  nt1.remove(ID_to_member);
 
   if(is_reference(nt2))
     nt2.remove(ID_C_reference);
-  nt2.remove("to-member");
+  nt2.remove(ID_to_member);
 
   // substitute final subtypes
   std::vector<typet> snt1;
@@ -1727,7 +1729,7 @@ bool cpp_typecheckt::dynamic_typecast(
   }
   else if(type.id()==ID_pointer)
   {
-    if(type.find("to-member").is_not_nil())
+    if(type.find(ID_to_member).is_not_nil())
       return false;
 
     if(type.subtype().id()==ID_empty)
@@ -1960,8 +1962,7 @@ bool cpp_typecheckt::static_typecast(
 
   if(type.id()==ID_pointer && e.type().id()==ID_pointer)
   {
-    if(type.find("to-member").is_nil()
-       && e.type().find("to-member").is_nil())
+    if(type.find(ID_to_member).is_nil() && e.type().find(ID_to_member).is_nil())
     {
       typet to=follow(type.subtype());
       typet from=follow(e.type().subtype());
@@ -1994,19 +1995,18 @@ bool cpp_typecheckt::static_typecast(
 
       return false;
     }
-    else if(type.find("to-member").is_not_nil() &&
-            e.type().find("to-member").is_not_nil())
+    else if(
+      type.find(ID_to_member).is_not_nil() &&
+      e.type().find(ID_to_member).is_not_nil())
     {
       if(type.subtype()!=e.type().subtype())
         return false;
 
-      struct_typet from_struct=
-        to_struct_type(
-          follow(static_cast<const typet&>(e.type().find("to-member"))));
+      struct_typet from_struct = to_struct_type(
+        follow(static_cast<const typet &>(e.type().find(ID_to_member))));
 
-      struct_typet to_struct=
-        to_struct_type(
-          follow(static_cast<const typet&>(type.find("to-member"))));
+      struct_typet to_struct = to_struct_type(
+        follow(static_cast<const typet &>(type.find(ID_to_member))));
 
       if(subtype_typecast(from_struct, to_struct))
       {
@@ -2016,17 +2016,17 @@ bool cpp_typecheckt::static_typecast(
       }
     }
     else if(
-      type.find("to-member").is_nil() &&
-      e.type().find("to-member").is_not_nil())
+      type.find(ID_to_member).is_nil() &&
+      e.type().find(ID_to_member).is_not_nil())
     {
       if(type.subtype() != e.type().subtype())
         return false;
 
       struct_typet from_struct = to_struct_type(
-        follow(static_cast<const typet &>(e.type().find("to-member"))));
+        follow(static_cast<const typet &>(e.type().find(ID_to_member))));
 
       new_expr = e;
-      new_expr.type().add("to-member") = from_struct;
+      new_expr.type().add(ID_to_member) = from_struct;
 
       return true;
     }
diff --git a/src/cpp/cpp_typecheck_expr.cpp b/src/cpp/cpp_typecheck_expr.cpp
index 0e0985a3624..5201e52f8e2 100644
--- a/src/cpp/cpp_typecheck_expr.cpp
+++ b/src/cpp/cpp_typecheck_expr.cpp
@@ -53,7 +53,7 @@ void cpp_typecheckt::typecheck_expr_main(exprt &expr)
     typecheck_expr_cpp_name(expr, cpp_typecheck_fargst());
   else if(expr.id()=="cpp-this")
     typecheck_expr_this(expr);
-  else if(expr.id()=="pointer-to-member")
+  else if(expr.id() == ID_pointer_to_member)
     convert_pmop(expr);
   else if(expr.id() == ID_new_object)
   {
@@ -718,7 +718,7 @@ void cpp_typecheckt::typecheck_expr_address_of(exprt &expr)
     {
       // it's a pointer to member function
       const struct_tag_typet symbol(code_type.get(ID_C_member_name));
-      expr.op0().type().add("to-member")=symbol;
+      expr.op0().type().add(ID_to_member) = symbol;
 
       if(code_type.get_bool(ID_C_is_virtual))
       {
@@ -733,7 +733,7 @@ void cpp_typecheckt::typecheck_expr_address_of(exprt &expr)
     expr.op0().id() == ID_ptrmember && expr.op0().op0().id() == "cpp-this")
   {
     expr.type() = pointer_type(expr.op0().type());
-    expr.type().add("to-member") = expr.op0().op0().type().subtype();
+    expr.type().add(ID_to_member) = expr.op0().op0().type().subtype();
     return;
   }
 
@@ -1999,7 +1999,7 @@ void cpp_typecheckt::typecheck_side_effect_function_call(
 
   if(expr.function().type().id()==ID_pointer)
   {
-    if(expr.function().type().find("to-member").is_not_nil())
+    if(expr.function().type().find(ID_to_member).is_not_nil())
     {
       const exprt &bound =
         static_cast<const exprt &>(expr.function().type().find(ID_C_bound));
@@ -2592,8 +2592,7 @@ void cpp_typecheckt::typecheck_expr_dereference(exprt &expr)
   exprt &op=expr.op0();
   const typet op_type=follow(op.type());
 
-  if(op_type.id()==ID_pointer &&
-     op_type.find("to-member").is_not_nil())
+  if(op_type.id() == ID_pointer && op_type.find(ID_to_member).is_not_nil())
   {
     error().source_location=expr.find_source_location();
     error() << "pointer-to-member must use "
@@ -2606,11 +2605,12 @@ void cpp_typecheckt::typecheck_expr_dereference(exprt &expr)
 
 void cpp_typecheckt::convert_pmop(exprt &expr)
 {
-  assert(expr.id()=="pointer-to-member");
-  assert(expr.operands().size() == 2);
+  PRECONDITION(expr.id() == ID_pointer_to_member);
+  PRECONDITION(expr.operands().size() == 2);
 
-  if(expr.op1().type().id()!=ID_pointer
-     || expr.op1().type().find("to-member").is_nil())
+  if(
+    expr.op1().type().id() != ID_pointer ||
+    expr.op1().type().find(ID_to_member).is_nil())
   {
     error().source_location=expr.source_location();
     error() << "pointer-to-member expected" << eom;
@@ -2620,7 +2620,7 @@ void cpp_typecheckt::convert_pmop(exprt &expr)
   typet t0=expr.op0().type().id()==ID_pointer ?
   expr.op0().type().subtype():  expr.op0().type();
 
-  typet t1((const typet&)expr.op1().type().find("to-member"));
+  typet t1((const typet &)expr.op1().type().find(ID_to_member));
 
   t0=follow(t0);
   t1=follow(t1);
diff --git a/src/cpp/cpp_typecheck_initializer.cpp b/src/cpp/cpp_typecheck_initializer.cpp
index eb9651b0926..ccc84862c10 100644
--- a/src/cpp/cpp_typecheck_initializer.cpp
+++ b/src/cpp/cpp_typecheck_initializer.cpp
@@ -123,7 +123,7 @@ void cpp_typecheckt::convert_initializer(symbolt &symbol)
           address_of_exprt(
             lookup(resolved_expr.get(ID_component_name)).symbol_expr());
 
-        symbol.value.type().add("to-member") = resolved_expr.op0().type();
+        symbol.value.type().add(ID_to_member) = resolved_expr.op0().type();
       }
       else
         UNREACHABLE;
@@ -142,8 +142,8 @@ void cpp_typecheckt::convert_initializer(symbolt &symbol)
 
     typecheck_expr(symbol.value);
 
-    if(symbol.value.type().find("to-member").is_not_nil())
-      symbol.type.add("to-member") = symbol.value.type().find("to-member");
+    if(symbol.value.type().find(ID_to_member).is_not_nil())
+      symbol.type.add(ID_to_member) = symbol.value.type().find(ID_to_member);
 
     if(symbol.value.id()==ID_initializer_list ||
        symbol.value.id()==ID_string_constant)
diff --git a/src/cpp/cpp_typecheck_type.cpp b/src/cpp/cpp_typecheck_type.cpp
index 84f5fda2fd1..a3a3aa3b265 100644
--- a/src/cpp/cpp_typecheck_type.cpp
+++ b/src/cpp/cpp_typecheck_type.cpp
@@ -85,12 +85,12 @@ void cpp_typecheckt::typecheck_type(typet &type)
     typecheck_type(type.subtype());
 
     // Check if it is a pointer-to-member
-    if(type.find("to-member").is_not_nil())
+    if(type.find(ID_to_member).is_not_nil())
     {
       // these can point either to data members or member functions
       // of a class
 
-      typet &class_object=static_cast<typet &>(type.add("to-member"));
+      typet &class_object = static_cast<typet &>(type.add(ID_to_member));
 
       if(class_object.id()==ID_cpp_name)
       {
diff --git a/src/cpp/expr2cpp.cpp b/src/cpp/expr2cpp.cpp
index c8649f56ba2..60b0e1fe423 100644
--- a/src/cpp/expr2cpp.cpp
+++ b/src/cpp/expr2cpp.cpp
@@ -259,12 +259,11 @@ std::string expr2cppt::convert_rec(
   {
     return "std::nullptr_t";
   }
-  else if(src.id()==ID_pointer &&
-          src.find("to-member").is_not_nil())
+  else if(src.id() == ID_pointer && src.find(ID_to_member).is_not_nil())
   {
     typet tmp=src;
     typet member;
-    member.swap(tmp.add("to-member"));
+    member.swap(tmp.add(ID_to_member));
 
     std::string dest="("+convert_rec(member, c_qualifierst(), "")+":: *)";
 
diff --git a/src/cpp/parse.cpp b/src/cpp/parse.cpp
index 4f816522c01..8a9f55f9341 100644
--- a/src/cpp/parse.cpp
+++ b/src/cpp/parse.cpp
@@ -3771,7 +3771,7 @@ bool Parser::rPtrToMember(irept &ptr_to_mem)
   #endif
 
   typet ptm(ID_frontend_pointer); // width gets set during conversion
-  irept &name = ptm.add("to-member");
+  irept &name = ptm.add(ID_to_member);
   name=cpp_namet();
   irept::subt &components=name.get_sub();
 
@@ -5377,7 +5377,7 @@ bool Parser::rPmExpr(exprt &exp)
     exprt left;
     left.swap(exp);
 
-    exp=exprt("pointer-to-member");
+    exp = exprt(ID_pointer_to_member);
     exp.move_to_operands(left, right);
     set_location(exp, tk);
   }
diff --git a/src/util/irep_ids.def b/src/util/irep_ids.def
index 692b64fbf4b..9eea3d33f2e 100644
--- a/src/util/irep_ids.def
+++ b/src/util/irep_ids.def
@@ -720,6 +720,8 @@ IREP_ID_ONE(template_decls)
 IREP_ID_ONE(throw_decl)
 IREP_ID_ONE(typeid)
 IREP_ID_TWO(C_quoted, #quoted)
+IREP_ID_ONE(to_member)
+IREP_ID_ONE(pointer_to_member)
 
 // Projects depending on this code base that wish to extend the list of
 // available ids should provide a file local_irep_ids.def in their source tree