diff --git a/src/igc.c b/src/igc.c
index e39aa70d1d7..c3e3c55f182 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -2947,6 +2947,8 @@ igc_xzalloc_ambig (size_t size)
   /* Not sure if xzalloc can ever return NULL here, depending on all the
      config options involved. Also not sure when it returns non-null for
      size 0. It does for me on macOS. */
+  while (size % IGC_ALIGN_DFLT)
+    size++;
   void *p = xzalloc (size);
   if (p == NULL)
     return NULL;