diff --git a/src/db/db/dbNetlistCompare.cc b/src/db/db/dbNetlistCompare.cc
index 4d33db900..20b5ac5ad 100644
--- a/src/db/db/dbNetlistCompare.cc
+++ b/src/db/db/dbNetlistCompare.cc
@@ -2105,7 +2105,7 @@ NetlistComparer::compare_circuits (const db::Circuit *c1, const db::Circuit *c2,
 
     std::sort (k.begin (), k.end ());
 
-    std::multimap<std::vector<std::pair<size_t, size_t> >, std::pair<const db::SubCircuit *, size_t> >::const_iterator scm = subcircuit_map.find (k);
+    std::multimap<std::vector<std::pair<size_t, size_t> >, std::pair<const db::SubCircuit *, size_t> >::iterator scm = subcircuit_map.find (k);
 
     if (! mapped || scm == subcircuit_map.end ()) {