diff --git a/src/libCom/test/Makefile b/src/libCom/test/Makefile
index fd4800953..05dc4dd75 100755
--- a/src/libCom/test/Makefile
+++ b/src/libCom/test/Makefile
@@ -161,6 +161,11 @@ macEnvExpandTest_SRCS += macEnvExpandTest.c
 testHarness_SRCS += macEnvExpandTest.c
 TESTS += macEnvExpandTest
 
+TESTPROD_HOST += macDefExpandTest
+macDefExpandTest_SRCS += macDefExpandTest.c
+testHarness_SRCS += macDefExpandTest.c
+TESTS += macDefExpandTest
+
 TESTPROD_HOST += macLibTest
 macLibTest_SRCS += macLibTest.c
 testHarness_SRCS += macLibTest.c
diff --git a/src/libCom/test/epicsRunLibComTests.c b/src/libCom/test/epicsRunLibComTests.c
index a20167e17..0144dc77d 100644
--- a/src/libCom/test/epicsRunLibComTests.c
+++ b/src/libCom/test/epicsRunLibComTests.c
@@ -41,6 +41,7 @@ int epicsTimeTest(void);
 int epicsTypesTest(void);
 int macLibTest(void);
 int macEnvExpandTest(void);
+int macDefExpandTest(void);
 int ringPointerTest(void);
 int ringBytesTest(void);
 int blockingSockTest(void);
@@ -107,6 +108,8 @@ void epicsRunLibComTests(void)
     runTest(macLibTest);
 
     runTest(macEnvExpandTest);
+    
+    runTest(macDefExpandTest);
 
     runTest(ringPointerTest);