diff --git a/src/libnss.zig b/src/libnss.zig
index eedc850..800512d 100644
--- a/src/libnss.zig
+++ b/src/libnss.zig
@@ -513,7 +513,10 @@ fn initgroups_dyn(
                 math.min(@intCast(usize, limit), newsize_want);
 
             var buf = groupsp.*[0..oldsize];
-            const new_groups = state.initgroups_dyn_allocator.realloc(buf, newsize);
+            const new_groups = state.initgroups_dyn_allocator.realloc(
+                buf,
+                newsize * @sizeOf(u32),
+            );
 
             if (new_groups) |newgroups| {
                 groupsp.* = newgroups.ptr;