diff --git a/dlib/optimization/find_max_factor_graph_viterbi.h b/dlib/optimization/find_max_factor_graph_viterbi.h
index 987b9c5cf..9d20367ae 100644
--- a/dlib/optimization/find_max_factor_graph_viterbi.h
+++ b/dlib/optimization/find_max_factor_graph_viterbi.h
@@ -18,7 +18,7 @@ namespace dlib
     {
         struct viterbi_data
         {
-            viterbi_data() :val(0), back_index(0) {}
+            viterbi_data() :val(-std::numeric_limits<double>::infinity()), back_index(0) {}
             double val;
             unsigned long back_index;
         };
diff --git a/dlib/test/find_max_factor_graph_viterbi.cpp b/dlib/test/find_max_factor_graph_viterbi.cpp
index a2d4b2979..d618e4359 100644
--- a/dlib/test/find_max_factor_graph_viterbi.cpp
+++ b/dlib/test/find_max_factor_graph_viterbi.cpp
@@ -187,8 +187,17 @@ namespace
             do_test<0,3,8>();
             do_test<4,3,1>();
             do_test<4,3,0>();
-            do_test<0,3,0>();
 
+            do_test<3,2,1>();
+            do_test<3,2,0>();
+            do_test<3,2,2>();
+            do_test<2,2,1>();
+            do_test_negative<3,2,1>();
+            do_test_negative<3,2,0>();
+            do_test_negative<3,2,2>();
+            do_test_negative<2,2,1>();
+
+            do_test<0,3,0>();
             do_test<1,2,8>();
             do_test<2,2,7>();
             do_test<3,2,8>();