diff --git a/bin/ruby-build b/bin/ruby-build
index 21a4e2ec..90523a9c 100755
--- a/bin/ruby-build
+++ b/bin/ruby-build
@@ -1268,7 +1268,7 @@ build_package_enable_yjit() {
   local rustc_ver="$(rustc --version 2>/dev/null)"
   [ -n "$rustc_ver" ] || return 0
   # Some kind of built-in bash comparison for dotted version strings would be awesome.
-  if [[ "${rustc_ver})" == *"rustc 1."[6789]* ]]; then
+  if [[ "${rustc_ver}" == *"rustc 1."[6789]* ]]; then
     echo "Building with YJIT by default because ${rustc_ver} is installed; add RUBY_CONFIGURE_OPTS='--disable-yjit' to disable explicitly" >&3
     package_option ruby configure --enable-yjit
   else