diff --git a/ChangeLog b/ChangeLog
index ff9349f4e3..20f69c9e38 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-12-21  Istvan Kurucsai <pistukem@gmail.com>
+
+	* malloc/malloc.c (munmap_chunk): Verify chunk alignment.
+
 2018-12-20  Istvan Kurucsai <pistukem@gmail.com>
 
 	* malloc/malloc.c (mremap_chunk): Additional checks.
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 32d47f083c..c33709e966 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -2889,6 +2889,7 @@ systrim (size_t pad, mstate av)
 static void
 munmap_chunk (mchunkptr p)
 {
+  size_t pagesize = GLRO (dl_pagesize);
   INTERNAL_SIZE_T size = chunksize (p);
 
   assert (chunk_is_mmapped (p));
@@ -2898,6 +2899,7 @@ munmap_chunk (mchunkptr p)
   if (DUMPED_MAIN_ARENA_CHUNK (p))
     return;
 
+  uintptr_t mem = (uintptr_t) chunk2mem (p);
   uintptr_t block = (uintptr_t) p - prev_size (p);
   size_t total_size = prev_size (p) + size;
   /* Unfortunately we have to do the compilers job by hand here.  Normally
@@ -2905,7 +2907,8 @@ munmap_chunk (mchunkptr p)
      page size.  But gcc does not recognize the optimization possibility
      (in the moment at least) so we combine the two values into one before
      the bit test.  */
-  if (__builtin_expect (((block | total_size) & (GLRO (dl_pagesize) - 1)) != 0, 0))
+  if (__glibc_unlikely ((block | total_size) & (pagesize - 1)) != 0
+      || __glibc_unlikely (!powerof2 (mem & (pagesize - 1))))
     malloc_printerr ("munmap_chunk(): invalid pointer");
 
   atomic_decrement (&mp_.n_mmaps);