diff --git a/src/libCom/osi/epicsReadline.c b/src/libCom/osi/epicsReadline.c
index 7cc569014..d410ac91e 100644
--- a/src/libCom/osi/epicsReadline.c
+++ b/src/libCom/osi/epicsReadline.c
@@ -59,7 +59,7 @@ static void osdReadlineEnd(struct readlineContext * c) {}
 void * epicsShareAPI
 epicsReadlineBegin(FILE *in)
 {
-    struct readlineContext *readlineContext = malloc(sizeof *readlineContext);
+    struct readlineContext *readlineContext = calloc(1, sizeof(*readlineContext));
 
     if (readlineContext) {
         readlineContext->in = in;