diff --git a/rust.spec b/rust.spec
index 780dcf1..83c3657 100644
--- a/rust.spec
+++ b/rust.spec
@@ -196,7 +196,7 @@ sed -e 's:<cargo-bin>:%{cargo_bin}:g' \
 
 %build
 export CPPFLAGS="%{optflags}" # eliminate complain from RPMlint
-./x.py build --config config.toml
+RUST_BACKTRACE=1 ./x.py build --config config.toml
 ./x.py doc --config config.toml
 
 %install