diff --git a/Expression.pas b/Expression.pas
index 405eb9b..6752380 100644
--- a/Expression.pas
+++ b/Expression.pas
@@ -805,8 +805,14 @@ var
    fToken := token;
    NextToken;
 
+   {in the preprocessor, all identifiers (post macro replacement) become 0}
+   if kind = preprocessorExpression then begin
+      stack^.token.kind := longconst;
+      stack^.token.lval := 0;
+      end {if}
+
    {if the id is not declared, create a function returning integer}
-   if id = nil then begin
+   else if id = nil then begin
       if token.kind = lparench then begin
          fnPtr := pointer(GCalloc(sizeof(typeRecord)));
          {fnPtr^.size := 0;}
@@ -827,10 +833,6 @@ var
          if ((lint & lintUndefFn) <> 0) or ((lint & lintC99Syntax) <> 0) then
             Error(51);
          end {if}
-      else if kind = preprocessorExpression then begin
-         stack^.token.kind := intconst;
-         stack^.token.ival := 0;
-         end {else if}
       else begin
          Error(31);
          errorFound := true;
diff --git a/cc.notes b/cc.notes
index 661989e..1be7cbf 100644
--- a/cc.notes
+++ b/cc.notes
@@ -965,6 +965,8 @@ int foo(int[42]);
 
 125. Within character constants, /* or // should not start a comment.
 
+126. In a proprocessor expression, any identifiers remaining after macro expansion should be replaced with the constant 0.  This did not work correctly for declared variable or function names, nor for enumeration constants.
+
 -- Bugs from C 2.1.0 that have been fixed -----------------------------------
 
 1.  In some situations, fread() reread the first 1K or so of the file.