diff --git a/docs/Howto.md b/docs/Howto.md
index 8e29d3e47..55f37034c 100644
--- a/docs/Howto.md
+++ b/docs/Howto.md
@@ -115,10 +115,10 @@ jtest:tracker_ms | int | 200 | Time spent during tracking
 jtest:tracker_spread | double | 0.25 | Spread of time spent during tracking
 jtest:tracker_bytes | int | 1000 | Bytes written during tracking
 jtest:tracker_bytes_spread | double | 0.25 | Spread of bytes written during tracking
-jtest:plotter_ms | int | 20 | Time spent during plotting
+jtest:plotter_ms | int | 0 | Time spent during plotting
 jtest:plotter_spread | double | 0.25 | Spread of time spent during plotting
 jtest:plotter_bytes | int | 1000 | Bytes written during plotting
-jtest:plotter_bytes_spread | int | 0.25 | Spread of bytes written during plotting
+jtest:plotter_bytes_spread | double | 0.25 | Spread of bytes written during plotting
 
 
 
diff --git a/src/plugins/JTest/JTestPlotter.h b/src/plugins/JTest/JTestPlotter.h
index 6ce1617b5..53a250b77 100644
--- a/src/plugins/JTest/JTestPlotter.h
+++ b/src/plugins/JTest/JTestPlotter.h
@@ -8,13 +8,15 @@
 #include <JANA/JApplication.h>
 #include <JANA/JEventProcessor.h>
 #include "JTestTracker.h"
+#include <mutex>
 
 class JTestPlotter : public JEventProcessor {
 
-    size_t m_cputime_ms = 20;
+    size_t m_cputime_ms = 0;
     size_t m_write_bytes = 1000;
     double m_cputime_spread = 0.25;
     double m_write_spread = 0.25;
+    std::mutex m_mutex;
 
 public:
 
@@ -42,6 +44,9 @@ class JTestPlotter : public JEventProcessor {
         // Read the extra data objects inserted by JTestTracker
         aEvent->Get<JTestTracker::JTestTrackAuxilliaryData>();
 
+        // Everything that happens after here is in a critical section
+        std::lock_guard<std::mutex> lock(m_mutex);
+
         // Consume CPU
         consume_cpu_ms(m_cputime_ms, m_cputime_spread);