diff --git a/libc/sock/recvfrom.c b/libc/sock/recvfrom.c
index 98cd7317e..27fac1ed6 100644
--- a/libc/sock/recvfrom.c
+++ b/libc/sock/recvfrom.c
@@ -84,10 +84,14 @@ ssize_t recvfrom(int fd, void *buf, size_t size, int flags,
   }
 
   if (rc != -1) {
-    if (IsBsd()) {
-      __convert_bsd_to_sockaddr(&addr);
+    if (addrsize) {
+      if (IsBsd()) {
+        __convert_bsd_to_sockaddr(&addr);
+      }
+      __write_sockaddr(&addr, opt_out_srcaddr, opt_inout_srcaddrsize);
+    } else {
+      *opt_inout_srcaddrsize = 0;
     }
-    __write_sockaddr(&addr, opt_out_srcaddr, opt_inout_srcaddrsize);
   }
 
   END_CANCELATION_POINT;