1 files changed, 2 insertions, 1 deletions
diff --git a/src/libstore/store.cc b/src/libstore/store.cc
index 73c09b27442f..59d4430fd692 100644
--- a/src/libstore/store.cc
+++ b/src/libstore/store.cc
@@ -164,7 +164,8 @@ void copyPath(const Path & src, const Path & dst)
         throw SysError("waiting for child");
 
     if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
-        throw Error("cannot copy file: child died");
+        throw Error(format("cannot copy `%1% to `%2%': child %3%")
+            % src % dst % statusToString(status));
 }