diff --git a/Dockerfile.custom b/Dockerfile.custom
index 75ba319..bf271fb 100644
--- a/Dockerfile.custom
+++ b/Dockerfile.custom
@@ -14,7 +14,7 @@ RUN mkdir -p /root/.cargo && cat > /root/.cargo/config.toml <<'EOF'
 [profile.release]
 lto = true
 codegen-units = 1
-opt-level = '3'
+opt-level = 3
 panic = "abort"
 strip = true