diff --git a/include/alloc_buffer.h b/include/alloc_buffer.h
index be33e8b68c..1c1dbe0a46 100644
--- a/include/alloc_buffer.h
+++ b/include/alloc_buffer.h
@@ -248,9 +248,9 @@ __alloc_buffer_alloc (struct alloc_buffer *buf, size_t size, size_t align)
   if (size == 1 && align == 1)
     return alloc_buffer_alloc_bytes (buf, size);
 
-  size_t current = buf->__alloc_buffer_current;
-  size_t aligned = roundup (current, align);
-  size_t new_current = aligned + size;
+  uintptr_t current = buf->__alloc_buffer_current;
+  uintptr_t aligned = roundup (current, align);
+  uintptr_t new_current = aligned + size;
   if (aligned >= current        /* No overflow in align step.  */
       && new_current >= size    /* No overflow in size computation.  */
       && new_current <= buf->__alloc_buffer_end) /* Room in buffer.  */
@@ -282,8 +282,8 @@ __alloc_buffer_next (struct alloc_buffer *buf, size_t align)
   if (align == 1)
     return (const void *) buf->__alloc_buffer_current;
 
-  size_t current = buf->__alloc_buffer_current;
-  size_t aligned = roundup (current, align);
+  uintptr_t current = buf->__alloc_buffer_current;
+  uintptr_t aligned = roundup (current, align);
   if (aligned >= current        /* No overflow in align step.  */
       && aligned <= buf->__alloc_buffer_end) /* Room in buffer.  */
     {
diff --git a/malloc/alloc_buffer_alloc_array.c b/malloc/alloc_buffer_alloc_array.c
index d8c08d03ea..b5f32bb630 100644
--- a/malloc/alloc_buffer_alloc_array.c
+++ b/malloc/alloc_buffer_alloc_array.c
@@ -23,12 +23,12 @@ void *
 __libc_alloc_buffer_alloc_array (struct alloc_buffer *buf, size_t element_size,
                                  size_t align, size_t count)
 {
-  size_t current = buf->__alloc_buffer_current;
+  uintptr_t current = buf->__alloc_buffer_current;
   /* The caller asserts that align is a power of two.  */
-  size_t aligned = ALIGN_UP (current, align);
+  uintptr_t aligned = ALIGN_UP (current, align);
   size_t size;
   bool overflow = __builtin_mul_overflow (element_size, count, &size);
-  size_t new_current = aligned + size;
+  uintptr_t new_current = aligned + size;
   if (!overflow                /* Multiplication did not overflow.  */
       && aligned >= current    /* No overflow in align step.  */
       && new_current >= size   /* No overflow in size computation.  */