diff --git a/NEWS b/NEWS
index d96969b286f9f..9f12b6d73f0a7 100644
--- a/NEWS
+++ b/NEWS
@@ -33,6 +33,10 @@ PHP                                                                        NEWS
   . Fixed bug GH-20732 (Phar::LoadPhar undefined behavior when reading fails).
     (ndossche)
 
+- POSIX:
+  . Fixed crash on posix groups to php array creation on macos.
+    (David Carlier)
+
 - SPL:
   . Fixed bug GH-20678 (resource created by GlobIterator crashes with fclose()).
     (David Carlier)
diff --git a/ext/posix/posix.c b/ext/posix/posix.c
index 2c87fbd28d981..85ea03d8cc0cb 100644
--- a/ext/posix/posix.c
+++ b/ext/posix/posix.c
@@ -678,7 +678,8 @@ int php_posix_group_to_array(struct group *g, zval *array_group) /* {{{ */
 	for (count = 0;; count++) {
 		/* gr_mem entries may be misaligned on macos. */
 		char *gr_mem;
-		memcpy(&gr_mem, &g->gr_mem[count], sizeof(char *));
+		char *entry = (char *)g->gr_mem + (count * sizeof (char *));
+		memcpy(&gr_mem, entry, sizeof(char *));
 		if (!gr_mem) {
 			break;
 		}