diff --git a/ginac/normal.cpp b/ginac/normal.cpp
index 97bd156..3e3635a 100644
--- a/ginac/normal.cpp
+++ b/ginac/normal.cpp
@@ -2006,8 +2006,11 @@ ex sqrfree_parfrac(const ex & a, const symbol & x)
  *  @see ex::normal */
 static ex replace_with_symbol(const ex & e, exmap & repl, exmap & rev_lookup)
 {
+        // Since the repl contains replaced expressions we should search for them
+	ex e_replaced = e.subs(repl, subs_options::no_pattern);
+
 	// Expression already replaced? Then return the assigned symbol
-	exmap::const_iterator it = rev_lookup.find(e);
+	exmap::const_iterator it = rev_lookup.find(e_replaced);
 	if (it != rev_lookup.end())
 		return it->second;
 	
@@ -2015,7 +2018,6 @@ static ex replace_with_symbol(const ex & e, exmap & repl, exmap & rev_lookup)
 	// replacement expression doesn't itself contain symbols from repl,
 	// because subs() is not recursive
 	ex es = (new symbol)->setflag(status_flags::dynallocated);
-	ex e_replaced = e.subs(repl, subs_options::no_pattern);
 	repl.insert(std::make_pair(es, e_replaced));
 	rev_lookup.insert(std::make_pair(e_replaced, es));
 	return es;
@@ -2028,16 +2030,18 @@ static ex replace_with_symbol(const ex & e, exmap & repl, exmap & rev_lookup)
  *  @see basic::to_polynomial */
 static ex replace_with_symbol(const ex & e, exmap & repl)
 {
+        // Since the repl contains replaced expressions we should search for them
+	ex e_replaced = e.subs(repl, subs_options::no_pattern);
+
 	// Expression already replaced? Then return the assigned symbol
 	for (exmap::const_iterator it = repl.begin(); it != repl.end(); ++it)
-		if (it->second.is_equal(e))
+		if (it->second.is_equal(e_replaced))
 			return it->first;
 	
 	// Otherwise create new symbol and add to list, taking care that the
 	// replacement expression doesn't itself contain symbols from repl,
 	// because subs() is not recursive
 	ex es = (new symbol)->setflag(status_flags::dynallocated);
-	ex e_replaced = e.subs(repl, subs_options::no_pattern);
 	repl.insert(std::make_pair(es, e_replaced));
 	return es;
 }