diff --git a/fs/incfs/data_mgmt.h b/fs/incfs/data_mgmt.h
index a3e4387bc613..7e80833ab42a 100644
--- a/fs/incfs/data_mgmt.h
+++ b/fs/incfs/data_mgmt.h
@@ -427,7 +427,7 @@ static inline struct inode_info *get_incfs_node(struct inode *inode)
 	if (!inode)
 		return NULL;
 
-	if (inode->i_sb->s_magic != (long) INCFS_MAGIC_NUMBER) {
+	if (inode->i_sb->s_magic != INCFS_MAGIC_NUMBER) {
 		/* This inode doesn't belong to us. */
 		pr_warn_once("incfs: %s on an alien inode.", __func__);
 		return NULL;
diff --git a/include/uapi/linux/incrementalfs.h b/include/uapi/linux/incrementalfs.h
index 6e157c603607..e22094b3ce85 100644
--- a/include/uapi/linux/incrementalfs.h
+++ b/include/uapi/linux/incrementalfs.h
@@ -18,7 +18,14 @@
 
 /* ===== constants ===== */
 #define INCFS_NAME "incremental-fs"
-#define INCFS_MAGIC_NUMBER (unsigned long)(0x5346434e49ul)
+
+/*
+ * Magic number used in file header and in memory superblock
+ * Note that it is a 5 byte unsigned long. Thus on 32 bit kernels, it is
+ * truncated to a 4 byte number
+ */
+#define INCFS_MAGIC_NUMBER (0x5346434e49ul & ULONG_MAX)
+
 #define INCFS_DATA_FILE_BLOCK_SIZE 4096
 #define INCFS_HEADER_VER 1