diff --git a/src/libCom/test/epicsStdioTest.c b/src/libCom/test/epicsStdioTest.c
index 011e67023..974b9683b 100644
--- a/src/libCom/test/epicsStdioTest.c
+++ b/src/libCom/test/epicsStdioTest.c
@@ -36,7 +36,7 @@ static void testEpicsSnprintf() {
     const char *svalue = "OneTwoThreeFour";
     const char *format = "int %d float %8.2e string %s";
     const char *expected = exbuffer;
-    size_t size;
+    int size;
     int rtn, rlen;
     
     sprintf(exbuffer, format, ivalue, fvalue, svalue);