diff --git a/src/libstore/path-references.cc b/src/libstore/path-references.cc
index 3d783bbe4be..9571da65cd9 100644
--- a/src/libstore/path-references.cc
+++ b/src/libstore/path-references.cc
@@ -124,7 +124,7 @@ void scanForReferencesDeep(
         case SourceAccessor::tFifo:
         case SourceAccessor::tUnknown:
         default:
-            throw Error("file '%s' has an unsupported type", path.abs());
+            throw Error("file '%s' has an unsupported type", accessor.showPath(path));
         }
     };
 
diff --git a/src/libutil/nar-listing.cc b/src/libutil/nar-listing.cc
index 1483c7a0c8e..358256bf0c9 100644
--- a/src/libutil/nar-listing.cc
+++ b/src/libutil/nar-listing.cc
@@ -157,7 +157,8 @@ static ListNarResult<deep> listNarImpl(SourceAccessor & accessor, const CanonPat
     case SourceAccessor::Type::tSocket:
     case SourceAccessor::Type::tFifo:
     case SourceAccessor::Type::tUnknown:
-        assert(false); // cannot happen for NARs
+    default:
+        throw Error("file '%s' has an unsupported type", accessor.showPath(path));
     }
 }