diff --git a/mm/nommu.c b/mm/nommu.c
index 8bdde95..6a2a8aa 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -497,15 +497,17 @@
 	    (flags & MAP_TYPE) != MAP_SHARED)
 		return -EINVAL;
 
-	if (PAGE_ALIGN(len) == 0)
-		return addr;
-
-	if (len > TASK_SIZE)
+	if (!len)
 		return -EINVAL;
 
+	/* Careful about overflows.. */
+	len = PAGE_ALIGN(len);
+	if (!len || len > TASK_SIZE)
+		return -ENOMEM;
+
 	/* offset overflow? */
 	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
-		return -EINVAL;
+		return -EOVERFLOW;
 
 	if (file) {
 		/* validate file mapping requests */