diff -up preprocessCore/preprocessCore/src/common.h.gcc10 preprocessCore/preprocessCore/src/common.h
--- preprocessCore/preprocessCore/src/common.h.gcc10	2020-02-01 10:08:31.173744264 -0500
+++ preprocessCore/preprocessCore/src/common.h	2020-02-01 10:10:05.071790093 -0500
@@ -0,0 +1,9 @@
+#ifndef COMMON_H
+#define COMMON_H 1
+
+#ifdef USE_PTHREADS
+#include <pthread.h>
+extern pthread_mutex_t mutex_R;
+#endif
+
+#endif
diff -up preprocessCore/preprocessCore/src/rma_background4.c.gcc10 preprocessCore/preprocessCore/src/rma_background4.c
--- preprocessCore/preprocessCore/src/rma_background4.c.gcc10	2020-02-01 10:10:33.526197917 -0500
+++ preprocessCore/preprocessCore/src/rma_background4.c	2020-02-01 10:11:25.274120949 -0500
@@ -44,13 +44,13 @@
 
 #include "weightedkerneldensity.h"
 #include "rma_background4.h"
+#include "common.h"
 
 #ifdef USE_PTHREADS
 #include <pthread.h>
 #include <limits.h>
 #include <unistd.h>
 #define THREADS_ENV_VAR "R_THREADS"
-pthread_mutex_t mutex_R;
 struct loop_data{
   double *data;
   size_t rows;
diff -up preprocessCore/preprocessCore/src/R_subColSummarize.c.gcc10 preprocessCore/preprocessCore/src/R_subColSummarize.c
--- preprocessCore/preprocessCore/src/R_subColSummarize.c.gcc10	2020-02-01 10:11:39.257829925 -0500
+++ preprocessCore/preprocessCore/src/R_subColSummarize.c	2020-02-01 10:11:59.747403514 -0500
@@ -37,13 +37,13 @@
 #include "median.h"
 
 #include "medianpolish.h"
+#include "common.h"
 
 #ifdef USE_PTHREADS
 #include <pthread.h>
 #include <limits.h>
 #include <unistd.h>
 #define THREADS_ENV_VAR "R_THREADS"
-pthread_mutex_t mutex_R;
 struct loop_data{
   double *matrix;
   double *results;
diff -up preprocessCore/preprocessCore/src/R_subrcModel_interfaces.c.gcc10 preprocessCore/preprocessCore/src/R_subrcModel_interfaces.c
--- preprocessCore/preprocessCore/src/R_subrcModel_interfaces.c.gcc10	2020-02-01 10:12:20.858964153 -0500
+++ preprocessCore/preprocessCore/src/R_subrcModel_interfaces.c	2020-02-01 10:12:36.248643869 -0500
@@ -26,7 +26,7 @@
 #include "rlm_se.h"
 #include "psi_fns.h"
 #include "medianpolish.h"
-
+#include "common.h"
 
 
 
@@ -37,7 +37,6 @@
 #include <limits.h>
 #include <unistd.h>
 #define THREADS_ENV_VAR "R_THREADS"
-pthread_mutex_t mutex_R;
 struct loop_data{
   double *matrix;
   SEXP *R_return_value;