diff --git a/ext/ffi_c/Buffer.c b/ext/ffi_c/Buffer.c
index faf4834d0..6863dda07 100644
--- a/ext/ffi_c/Buffer.c
+++ b/ext/ffi_c/Buffer.c
@@ -114,7 +114,7 @@ buffer_initialize(int argc, VALUE* argv, VALUE self)
         }
 
         /* ensure the memory is aligned on at least a 8 byte boundary */
-        p->memory.address = (void *) (((uintptr_t) p->data.storage + 0x7) & (uintptr_t) ~0x7UL);
+        p->memory.address = (void *) (((uintptr_t) p->data.storage + 0x7) & (uintptr_t) ~0x7ULL);
     
         if (p->memory.size > 0 && (nargs < 3 || RTEST(rbClear))) {
             memset(p->memory.address, 0, p->memory.size);
@@ -154,7 +154,7 @@ buffer_initialize_copy(VALUE self, VALUE other)
         return Qnil;
     }
     
-    dst->memory.address = (void *) (((uintptr_t) dst->data.storage + 0x7) & (uintptr_t) ~0x7UL);
+    dst->memory.address = (void *) (((uintptr_t) dst->data.storage + 0x7) & (uintptr_t) ~0x7ULL);
     dst->memory.size = src->size;
     dst->memory.typeSize = src->typeSize;
     
diff --git a/ext/ffi_c/MemoryPointer.c b/ext/ffi_c/MemoryPointer.c
index 0d91c35b7..9dc59bb57 100644
--- a/ext/ffi_c/MemoryPointer.c
+++ b/ext/ffi_c/MemoryPointer.c
@@ -112,7 +112,7 @@ memptr_malloc(VALUE self, long size, long count, bool clear)
     p->memory.typeSize = (int) size;
     p->memory.size = msize;
     /* ensure the memory is aligned on at least a 8 byte boundary */
-    p->memory.address = (char *) (((uintptr_t) p->storage + 0x7) & (uintptr_t) ~0x7UL);;
+    p->memory.address = (char *) (((uintptr_t) p->storage + 0x7) & (uintptr_t) ~0x7ULL);
     p->allocated = true;
 
     if (clear && p->memory.size > 0) {
diff --git a/ext/ffi_c/Pointer.c b/ext/ffi_c/Pointer.c
index 1eee790db..e5f24a4dc 100644
--- a/ext/ffi_c/Pointer.c
+++ b/ext/ffi_c/Pointer.c
@@ -183,7 +183,7 @@ ptr_initialize_copy(VALUE self, VALUE other)
     
     dst->allocated = true;
     dst->autorelease = true;
-    dst->memory.address = (void *) (((uintptr_t) dst->storage + 0x7) & (uintptr_t) ~0x7UL);
+    dst->memory.address = (void *) (((uintptr_t) dst->storage + 0x7) & (uintptr_t) ~0x7ULL);
     dst->memory.size = src->size;
     dst->memory.typeSize = src->typeSize;