diff --git a/lib/datadog/appsec/processor.rb b/lib/datadog/appsec/processor.rb
index ceebbfa8d81..a34bb5a653a 100644
--- a/lib/datadog/appsec/processor.rb
+++ b/lib/datadog/appsec/processor.rb
@@ -14,20 +14,23 @@ def initialize(processor)
           @time_ext_ns = 0.0
           @timeouts = 0
           @events = []
+          @run_mutex = Mutex.new
         end
 
         def run(input, timeout = WAF::LibDDWAF::DDWAF_RUN_TIMEOUT)
-          start_ns = Core::Utils::Time.get_time(:nanosecond)
+          @run_mutex.synchronize do
+            start_ns = Core::Utils::Time.get_time(:nanosecond)
 
-          # TODO: remove multiple assignment
-          _code, res = _ = @context.run(input, timeout)
-          # @type var res: WAF::Result
+            # TODO: remove multiple assignment
+            _code, res = _ = @context.run(input, timeout)
+            # @type var res: WAF::Result
 
-          stop_ns = Core::Utils::Time.get_time(:nanosecond)
+            stop_ns = Core::Utils::Time.get_time(:nanosecond)
 
-          @time_ns += res.total_runtime
-          @time_ext_ns += (stop_ns - start_ns)
-          @timeouts += 1 if res.timeout
+            @time_ns += res.total_runtime
+            @time_ext_ns += (stop_ns - start_ns)
+            @timeouts += 1 if res.timeout
+          end
 
           res
         end