diff --git a/lib/restate/vm.rb b/lib/restate/vm.rb
index 5fa7da5..3c22656 100644
--- a/lib/restate/vm.rb
+++ b/lib/restate/vm.rb
@@ -7,8 +7,13 @@
   RUBY_VERSION =~ /(\d+\.\d+)/
   require_relative "#{Regexp.last_match(1)}/restate_internal"
 rescue LoadError
-  # Fall back to the default location (development builds, source gem installs)
-  require_relative 'restate_internal'
+  begin
+    # rake compile output (ext.lib_dir = 'lib/restate' in Rakefile)
+    require_relative 'restate_internal'
+  rescue LoadError
+    # gem install from source: extconf.rb builds to lib/restate_internal
+    require_relative '../restate_internal'
+  end
 end
 
 module Restate
diff --git a/test-services/Dockerfile b/test-services/Dockerfile
index a19335b..8b330fc 100644
--- a/test-services/Dockerfile
+++ b/test-services/Dockerfile
@@ -26,9 +26,9 @@ RUN bundle install && bundle exec rake compile
 # ── Runtime stage ──
 FROM ruby:3.3-slim-bookworm AS test-services
 
-# Install build tools for native gem extensions (e.g. json)
+# Install build tools and OpenSSL dev headers for native gem extensions
 RUN apt-get update -y && \
-    apt-get install -y build-essential && \
+    apt-get install -y build-essential libssl-dev && \
     rm -rf /var/lib/apt/lists/*
 
 WORKDIR /usr/src/app