diff --git a/usr.bin/grep/util.c b/usr.bin/grep/util.c
index 1805cc74bfc6..936abc41b3ef 100644
--- a/usr.bin/grep/util.c
+++ b/usr.bin/grep/util.c
@@ -650,6 +650,8 @@ grep_malloc(size_t size)
 {
 	void *ptr;
 
+	if (size == 0)
+		return (NULL);
 	if ((ptr = malloc(size)) == NULL)
 		err(2, "malloc");
 	return (ptr);
@@ -663,6 +665,8 @@ grep_calloc(size_t nmemb, size_t size)
 {
 	void *ptr;
 
+	if (nmemb == 0 || size == 0)
+		return (NULL);
 	if ((ptr = calloc(nmemb, size)) == NULL)
 		err(2, "calloc");
 	return (ptr);