diff --git a/lib/instana/backend/request_client.rb b/lib/instana/backend/request_client.rb
index de6ac5ce..6955b437 100644
--- a/lib/instana/backend/request_client.rb
+++ b/lib/instana/backend/request_client.rb
@@ -8,8 +8,10 @@
 # :nocov:
 begin
   require 'oj'
+  INSTANA_USE_OJ = true
 rescue LoadError => _e
   Instana.logger.warn("Unable to load Oj.")
+  INSTANA_USE_OJ = false
 end
 # :nocov:
 
@@ -66,7 +68,7 @@ def send_request(method, path, data = nil, headers = {})
 
       def encode_body(data)
         # :nocov:
-        defined?(Oj) ? Oj.dump(data, mode: :strict) : JSON.dump(data)
+        INSTANA_USE_OJ ? Oj.dump(data, mode: :strict) : JSON.dump(data)
         # :nocov:
       end
     end