diff --git a/src/shctx.c b/src/shctx.c
index fe1b74a..ae9cc1f 100644
--- a/src/shctx.c
+++ b/src/shctx.c
@@ -308,6 +308,10 @@
 	if (maxblocks <= 0)
 		return 0;
 
+	/* make sure to align the records on a pointer size */
+	blocksize = (blocksize + sizeof(void *) - 1) & -sizeof(void *);
+	extra     = (extra     + sizeof(void *) - 1) & -sizeof(void *);
+
 #ifndef USE_PRIVATE_CACHE
 	if (shared)
 		maptype = MAP_SHARED;