diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 9f8c7092d..814028442 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -122,10 +122,6 @@ void deletePath(const Path & path);
 
 void deletePath(const Path & path, unsigned long long & bytesFreed);
 
-/* Create a temporary directory. */
-Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix",
-    bool includePid = true, bool useGlobalCounter = true, mode_t mode = 0755);
-
 std::string getUserName();
 
 /* Return $HOME or the user's home directory from /etc/passwd. */