diff --git a/Dockerfile.ci b/Dockerfile.ci
index d73fd2a6..cd7d6d1b 100644
--- a/Dockerfile.ci
+++ b/Dockerfile.ci
@@ -38,10 +38,11 @@ RUN mkdir -p /tmp/exla_warm/config && \
     printf 'import Config\nconfig :nx, :default_backend, EXLA.Backend\nconfig :exla, :make_args, ["-j1"]\n' > /tmp/exla_warm/config/config.exs
 
 # Compile all deps. EXLA's Makefile defaults to -O3 which OOM-kills g++
-# on low-memory CI runners. Patch it to -O0 before compilation.
+# on low-memory CI runners. Set DEBUG=1 so the Makefile uses -g
+# (debug symbols, low compile-time memory) instead of -O3 (heavy
+# optimization passes). Also set EXLA_CPU_ONLY=1 to skip nvcc probing.
 RUN mix deps.get && \
-    sed -i 's/-O3/-O0/g' deps/exla/Makefile && \
-    mix deps.compile
+    DEBUG=1 EXLA_CPU_ONLY=1 mix deps.compile
 
 # Save the full build cache (libexla.so + .o files + xla_extension lib)
 # so Make finds all targets already built when restored in the test step.