diff --git a/src/common/model/source_file.cc b/src/common/model/source_file.cc
index b5161c97..de121e77 100644
--- a/src/common/model/source_file.cc
+++ b/src/common/model/source_file.cc
@@ -31,6 +31,7 @@ std::string to_string(source_file_t sf)
         return "implementation";
     default:
         assert(false);
+        return "";
     }
 }
 
diff --git a/src/common/model/template_parameter.cc b/src/common/model/template_parameter.cc
index 662f6286..d3a80903 100644
--- a/src/common/model/template_parameter.cc
+++ b/src/common/model/template_parameter.cc
@@ -37,7 +37,8 @@ std::string to_string(template_parameter_kind_t k)
     case template_parameter_kind_t::concept_constraint:
         return "concept_constraint";
     default:
-        assert(0);
+        assert(false);
+        return "";
     }
 }