diff --git a/README b/README
index dac46f3..fb9d904 100644
--- a/README
+++ b/README
@@ -2149,6 +2149,13 @@ The following options need to be configured:
 
 		Timeout waiting for an ARP reply in milliseconds.
 
+		CONFIG_NFS_TIMEOUT
+
+		Timeout in milliseconds used in NFS protocol.
+		If you encounter "ERROR: Cannot umount" in nfs command,
+		try longer timeout such as
+		#define CONFIG_NFS_TIMEOUT 10000UL
+
 - Command Interpreter:
 		CONFIG_AUTO_COMPLETE
 
diff --git a/net/nfs.c b/net/nfs.c
index 5b99763..7f2393f 100644
--- a/net/nfs.c
+++ b/net/nfs.c
@@ -31,7 +31,11 @@
 
 #define HASHES_PER_LINE 65	/* Number of "loading" hashes per line	*/
 #define NFS_RETRY_COUNT 30
-#define NFS_TIMEOUT 2000UL
+#ifndef CONFIG_NFS_TIMEOUT
+# define NFS_TIMEOUT 2000UL
+#else
+# define NFS_TIMEOUT CONFIG_NFS_TIMEOUT
+#endif
 
 static int fs_mounted;
 static unsigned long rpc_id;