diff --git a/ci/script.sh b/ci/script.sh
index e87e50a8db..78341e1bba 100644
--- a/ci/script.sh
+++ b/ci/script.sh
@@ -37,7 +37,7 @@ main() {
     mkdir -p ci/builds
 
     if [ $T = x86_64-unknown-linux-gnu ]; then
-        if [ $TRAVIS_RUST_VERSION == 1.*.* ]; then
+        if [[ $TRAVIS_RUST_VERSION == 1.*.* ]]; then
             # test on a fixed version (MSRV) to avoid problems with changes in rustc diagnostics
             # compile-fail tests
             cargo test --test single --target $T