diff --git a/dlls/netapi32/access.c b/dlls/netapi32/access.c
index 255e51b315..7cd05fcbbe 100644
--- a/dlls/netapi32/access.c
+++ b/dlls/netapi32/access.c
@@ -437,7 +437,10 @@ NetUserGetLocalGroups(LPCWSTR servername, LPCWSTR username, DWORD level,
 
     size = UNLEN + 1;
     NetApiBufferAllocate(size * sizeof(WCHAR), (LPVOID*)&currentuser);
-    GetUserNameW(currentuser, &size);
+    if (!GetUserNameW(currentuser, &size)) {
+        NetApiBufferFree(currentuser);
+        return ERROR_NOT_ENOUGH_MEMORY;
+    }
 
     if (lstrcmpiW(username, currentuser) && NETAPI_FindUser(username))
     {
diff --git a/dlls/netapi32/local_group.c b/dlls/netapi32/local_group.c
index 7f7d3c1900..f4f42141e7 100644
--- a/dlls/netapi32/local_group.c
+++ b/dlls/netapi32/local_group.c
@@ -196,7 +196,9 @@ NET_API_STATUS WINAPI NetLocalGroupGetMembers(
         *entriesread = 0;
 
         userNameLen = MAX_COMPUTERNAME_LENGTH + 1;
-        GetUserNameW(userName,&userNameLen);
+        if (!GetUserNameW(userName,&userNameLen))
+            return ERROR_NOT_ENOUGH_MEMORY;
+
         needlen = sizeof(LOCALGROUP_MEMBERS_INFO_3) +
              (userNameLen+2) * sizeof(WCHAR);
         if (prefmaxlen != MAX_PREFERRED_LENGTH)