diff --git a/c/src/tests/psxtests/psx01/system.h b/c/src/tests/psxtests/psx01/system.h
index a0e2220827..35fef73269 100644
--- a/c/src/tests/psxtests/psx01/system.h
+++ b/c/src/tests/psxtests/psx01/system.h
@@ -19,6 +19,7 @@
 #include <pmacros.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sched.h>
 
 void *POSIX_Init(
   void *argument
@@ -37,6 +38,8 @@ void *Task_1_through_3(
 
 #define CONFIGURE_POSIX_INIT_THREAD_TABLE
 
+#define CONFIGURE_MAXIMUM_POSIX_THREADS     2
+
 #include <confdefs.h>
 
 /* global variables */
diff --git a/testsuites/psxtests/psx01/system.h b/testsuites/psxtests/psx01/system.h
index a0e2220827..35fef73269 100644
--- a/testsuites/psxtests/psx01/system.h
+++ b/testsuites/psxtests/psx01/system.h
@@ -19,6 +19,7 @@
 #include <pmacros.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sched.h>
 
 void *POSIX_Init(
   void *argument
@@ -37,6 +38,8 @@ void *Task_1_through_3(
 
 #define CONFIGURE_POSIX_INIT_THREAD_TABLE
 
+#define CONFIGURE_MAXIMUM_POSIX_THREADS     2
+
 #include <confdefs.h>
 
 /* global variables */