3 files changed, 4 insertions, 2 deletions
diff --git a/nix/libutil/archive.cc b/nix/libutil/archive.cc
index ab4cd47351..70a1c580dd 100644
--- a/nix/libutil/archive.cc
+++ b/nix/libutil/archive.cc
@@ -104,7 +104,7 @@ static void dump(const Path & path, Sink & sink, PathFilter & filter)
         writeString(readLink(path), sink);
     }
 
-    else throw Error(format("file `%1%' has an unknown type") % path);
+    else throw Error(format("file `%1%' has an unsupported type") % path);
 
     writeString(")", sink);
 }
diff --git a/nix/libutil/util.cc b/nix/libutil/util.cc
index 15c462ce4e..846674a29d 100644
--- a/nix/libutil/util.cc
+++ b/nix/libutil/util.cc
@@ -1041,7 +1041,7 @@ void expect(std::istream & str, const string & s)
     char s2[s.size()];
     str.read(s2, s.size());
     if (string(s2, s.size()) != s)
-        throw Error(format("expected string `%1%'") % s);
+        throw FormatError(format("expected string `%1%'") % s);
 }
 
 
diff --git a/nix/libutil/util.hh b/nix/libutil/util.hh
index 8bedfea9a0..ce2d77c19a 100644
--- a/nix/libutil/util.hh
+++ b/nix/libutil/util.hh
@@ -326,6 +326,8 @@ bool hasSuffix(const string & s, const string & suffix);
 /* Read string `s' from stream `str'. */
 void expect(std::istream & str, const string & s);
 
+MakeError(FormatError, Error)
+
 
 /* Read a C-style string from stream `str'. */
 string parseString(std::istream & str);