diff --git a/src/libCom/test/Makefile b/src/libCom/test/Makefile
index fadf89066..a0d47270b 100644
--- a/src/libCom/test/Makefile
+++ b/src/libCom/test/Makefile
@@ -70,7 +70,9 @@ TESTS += epicsTimeTest
 
 TESTPROD_HOST += epicsTimeZoneTest
 epicsTimeZoneTest_SRCS += epicsTimeZoneTest.c
+ifeq ($(OS_CLASS),RTEMS)
 testHarness_SRCS += epicsTimeZoneTest.cpp
+endif
 TESTS += epicsTimeZoneTest
 
 TESTPROD_HOST += epicsThreadTest
diff --git a/src/libCom/test/epicsRunLibComTests.c b/src/libCom/test/epicsRunLibComTests.c
index 73a491ae6..3b81b15cf 100644
--- a/src/libCom/test/epicsRunLibComTests.c
+++ b/src/libCom/test/epicsRunLibComTests.c
@@ -34,7 +34,9 @@ int epicsThreadOnceTest(void);
 int epicsThreadPriorityTest(void);
 int epicsThreadPrivateTest(void);
 int epicsTimeTest(void);
+#ifdef __rtems__
 int epicsTimeZoneTest(void);
+#endif
 int macLibTest(void);
 int macEnvExpandTest(void);
 int ringPointerTest(void);
@@ -90,7 +92,9 @@ void epicsRunLibComTests(void)
 
     runTest(epicsTimeTest);
 
+#ifdef __rtems__
     runTest(epicsTimeZoneTest);
+#endif
 
     runTest(macLibTest);