diff --git a/Source/portable/MemMang/heap_1.c b/Source/portable/MemMang/heap_1.c
index b99a3fb23..2de6cfca1 100644
--- a/Source/portable/MemMang/heap_1.c
+++ b/Source/portable/MemMang/heap_1.c
@@ -56,6 +56,11 @@ Changes between V2.6.1 and V3.0.0
 #include "task.h"
 
 /* Setup the correct byte alignment mask for the defined byte alignment. */
+
+#if portBYTE_ALIGNMENT == 8
+	#define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0007 )
+#endif
+
 #if portBYTE_ALIGNMENT == 4
 	#define heapBYTE_ALIGNMENT_MASK	( ( size_t ) 0x0003 )
 #endif
diff --git a/Source/portable/MemMang/heap_2.c b/Source/portable/MemMang/heap_2.c
index 6be0139e6..a3ccaa4f6 100644
--- a/Source/portable/MemMang/heap_2.c
+++ b/Source/portable/MemMang/heap_2.c
@@ -44,6 +44,11 @@
 #include "task.h"
 
 /* Setup the correct byte alignment mask for the defined byte alignment. */
+
+#if portBYTE_ALIGNMENT == 8
+	#define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0007 )
+#endif
+
 #if portBYTE_ALIGNMENT == 4
 	#define heapBYTE_ALIGNMENT_MASK	( ( size_t ) 0x0003 )
 #endif