diff --git a/modules/src/malloc/mal.c b/modules/src/malloc/mal.c
index 29ad660f5..253c7e581 100644
--- a/modules/src/malloc/mal.c
+++ b/modules/src/malloc/mal.c
@@ -39,6 +39,9 @@ malloc(n)
 	register mallink *ml;
 	register int min_class;
 
+	if (n == 0) {
+		return 0;
+	}
 	if (n < MIN_SIZE) n = align(MIN_SIZE); else n = align(n);
 #ifdef STORE
 	if (n <= MAX_STORE*MIN_SIZE)	{
@@ -234,6 +237,10 @@ realloc(addr, n)
 		*/
 		return malloc(n);
 	}
+	if (n == 0) {
+		free(addr);
+		return 0;
+	}
 	ml = mallink_of_block(addr);
 	if (n < MIN_SIZE) n = align(MIN_SIZE); else n = align(n);
 #ifdef STORE