diff --git a/builtin.c b/builtin.c
index 386b6ed..da457e2 100644
--- a/builtin.c
+++ b/builtin.c
@@ -98,7 +98,7 @@ fatal(_("attempt to use array `%s' in a scalar context"), array_vname(s1)); \
 
 /* efwrite --- like fwrite, but with error checking */
 
-static void
+void
 efwrite(const void *ptr,
 	size_t size,
 	size_t count,
@@ -108,11 +108,13 @@ efwrite(const void *ptr,
 	bool flush)
 {
 	errno = 0;
-	if (rp != NULL) {
-		if (rp->output.gawk_fwrite(ptr, size, count, fp, rp->output.opaque) != count)
+	if (count) {
+		if (rp != NULL) {
+			if (rp->output.gawk_fwrite(ptr, size, count, fp, rp->output.opaque) != count)
+				goto wrerror;
+		} else if (fwrite(ptr, size, count, fp) != count)
 			goto wrerror;
-	} else if (fwrite(ptr, size, count, fp) != count)
-		goto wrerror;
+	}
 	if (flush
 	  && ((fp == stdout && output_is_tty)
 	      || (rp != NULL && (rp->flag & RED_NOBUF) != 0))) {