diff --git a/lib/curl_share.c b/lib/curl_share.c
index 94469bc3ef..0b4ee9e367 100644
--- a/lib/curl_share.c
+++ b/lib/curl_share.c
@@ -61,7 +61,7 @@ static void share_destroy(struct Curl_share *share)
 #ifdef USE_MUTEX
   Curl_mutex_destroy(&share->lock);
 #endif
-  share->magic = 0;
+  curlx_memzero(share, sizeof(*share));
   curlx_free(share);
 }
 
diff --git a/lib/multi.c b/lib/multi.c
index d0fa68ab4c..772116e9f5 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -3043,6 +3043,7 @@ CURLMcode curl_multi_cleanup(CURLM *m)
     Curl_uint32_bset_destroy(&multi->pending);
     Curl_uint32_bset_destroy(&multi->msgsent);
     Curl_uint32_tbl_destroy(&multi->xfers);
+    curlx_memzero(multi, sizeof(*multi));
     curlx_free(multi);
 
     return CURLM_OK;
diff --git a/lib/url.c b/lib/url.c
index 3b0663515b..0ce9639c0e 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -315,6 +315,7 @@ CURLcode Curl_close(struct Curl_easy **datap)
 #ifndef CURL_DISABLE_PROXY
   Curl_ssl_config_cleanup(&data->set.proxy_ssl.primary);
 #endif
+  curlx_memzero(data, sizeof(*data));
   curlx_free(data);
   return CURLE_OK;
 }