diff --git a/motorApp/NewportSrc/devPM500.cc b/motorApp/NewportSrc/devPM500.cc
index daa05fa5..b077d58a 100644
--- a/motorApp/NewportSrc/devPM500.cc
+++ b/motorApp/NewportSrc/devPM500.cc
@@ -161,7 +161,7 @@ STATIC RTN_STATUS PM500_build_trans(motor_cmnd command, double *parms, struct mo
     char axis_name;
     char buff[110];
     int axis, card, maxdigits;
-    unsigned int size;
+    size_t size;
     double dval, cntrl_units;
     RTN_STATUS rtnval;
 
diff --git a/motorApp/NewportSrc/drvPM500.cc b/motorApp/NewportSrc/drvPM500.cc
index 9ae0804b..35354028 100644
--- a/motorApp/NewportSrc/drvPM500.cc
+++ b/motorApp/NewportSrc/drvPM500.cc
@@ -355,7 +355,7 @@ exit:
 static RTN_STATUS send_mess(int card, char const *com, char *name)
 {
     struct MMcontroller *cntrl;
-    int size;
+    size_t size;
     size_t nwrite;
 
     size = strlen(com);
@@ -437,7 +437,7 @@ static int recv_mess(int card, char *com, int flag)
     }
 
     Debug(2, "recv_mess(): message = \"%s\"\n", com);
-    return(nread);
+    return((int)nread);
 }