1 files changed, 1 insertions, 1 deletions
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 0a7c343d0..0dd4998d9 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -133,7 +133,7 @@ static int compatNixHash(int argc, char * * argv)
             string s = getArg(*arg, arg, end);
             ht = parseHashType(s);
             if (ht == htUnknown)
-                throw UsageError(format("unknown hash type '%1%'") % s);
+                throw UsageError("unknown hash type '%1%'", s);
         }
         else if (*arg == "--to-base16") op = opTo16;
         else if (*arg == "--to-base32") op = opTo32;