diff --git a/src/harfbuzz-impl.c b/src/harfbuzz-impl.c
index a3a55895a..ffcef8060 100644
--- a/src/harfbuzz-impl.c
+++ b/src/harfbuzz-impl.c
@@ -30,7 +30,7 @@
 
 
 HB_INTERNAL HB_Pointer
-_hb_alloc( HB_UInt   size,
+_hb_alloc( size_t    size,
 	   HB_Error *perror )
 {
   HB_Error    error = 0;
@@ -50,7 +50,7 @@ _hb_alloc( HB_UInt   size,
 
 HB_INTERNAL HB_Pointer
 _hb_realloc( HB_Pointer  block,
-	     HB_UInt     new_size,
+	     size_t      new_size,
 	     HB_Error   *perror )
 {
   HB_Pointer  block2 = NULL;
diff --git a/src/harfbuzz-impl.h b/src/harfbuzz-impl.h
index 0442e4e29..f886e676b 100644
--- a/src/harfbuzz-impl.h
+++ b/src/harfbuzz-impl.h
@@ -32,6 +32,8 @@
 
 #include "harfbuzz-global.h"
 
+#include <stdlib.h>
+
 HB_BEGIN_HEADER
 
 #ifndef HB_INTERNAL
@@ -95,12 +97,12 @@ HB_BEGIN_HEADER
 
 
 HB_INTERNAL HB_Pointer
-_hb_alloc( HB_UInt   size,
+_hb_alloc( size_t    size,
 	   HB_Error *perror_ );
 
 HB_INTERNAL HB_Pointer
 _hb_realloc( HB_Pointer block,
-	     HB_UInt    new_size,
+	     size_t     new_size,
 	     HB_Error  *perror_ );
 
 HB_INTERNAL void