diff --git a/backport-fixed-nine-bits-processing-updated-reset-code-behavi.patch b/backport-fixed-nine-bits-processing-updated-reset-code-behavi.patch
new file mode 100644
index 0000000000000000000000000000000000000000..0923f840bee0ff5f2c20ae06940ff8abd4c21440
--- /dev/null
+++ b/backport-fixed-nine-bits-processing-updated-reset-code-behavi.patch
@@ -0,0 +1,102 @@
+From 3303f310da2c59188fc93b79ed526cad75db323e Mon Sep 17 00:00:00 2001
+From: Andrew Aladjev <aladjev.andrew@gmail.com>
+Date: Mon, 8 Feb 2021 08:00:36 +0300
+Subject: [PATCH] fixed nine bits processing, updated reset code behaviour
+
+Closes #5.
+
+The problem is that extcode and maxcode together with n_bits were not properly
+ initialized and reset. I've added code in the same style as code around.
+---
+ compress.c        | 32 ++++++++++++++++++++++----------
+ tests/runtests.sh |  5 +++++
+ 2 files changed, 27 insertions(+), 10 deletions(-)
+
+diff --git a/compress.c b/compress.c
+index 66cacf1..dc5a006 100644
+--- a/compress.c
++++ b/compress.c
+@@ -402,6 +402,24 @@ union	bytes
+ 							(o) += (n);										\
+ 						}
+ 
++#define reset_n_bits_for_compressor(n_bits, stcode, free_ent, extcode, maxbits) {	\
++	n_bits = INIT_BITS;								\
++	stcode = 1;									\
++	free_ent = FIRST;								\
++	extcode = MAXCODE(n_bits);							\
++	if (n_bits < maxbits)								\
++		extcode++;								\
++}
++
++#define reset_n_bits_for_decompressor(n_bits, bitmask, maxbits, maxcode, maxmaxcode) {	\
++	n_bits = INIT_BITS;								\
++	bitmask = (1<<n_bits)-1;							\
++	if (n_bits == maxbits)								\
++		maxcode = maxmaxcode;							\
++	else										\
++		maxcode = MAXCODE(n_bits)-1;						\
++}
++
+ char			*progname;			/* Program name									*/
+ int 			silent = 0;			/* don't tell me about errors					*/
+ int 			quiet = 1;			/* don't tell me about compression 				*/
+@@ -1250,9 +1268,7 @@ compress(fdin, fdout)
+ 
+ 		ratio = 0;
+ 		checkpoint = CHECK_GAP;
+-		extcode = MAXCODE(n_bits = INIT_BITS)+1;
+-		stcode = 1;
+-		free_ent = FIRST;
++		reset_n_bits_for_compressor(n_bits, stcode, free_ent, extcode, maxbits);
+ 
+ 		memset(outbuf, 0, sizeof(outbuf));
+ 		bytes_out = 0; bytes_in = 0;
+@@ -1322,9 +1338,7 @@ compress(fdin, fdout)
+ 						output(outbuf,outbits,CLEAR,n_bits);
+ 						boff = outbits = (outbits-1)+((n_bits<<3)-
+ 								  	((outbits-boff-1+(n_bits<<3))%(n_bits<<3)));
+-						extcode = MAXCODE(n_bits = INIT_BITS)+1;
+-						free_ent = FIRST;
+-						stcode = 1;
++						reset_n_bits_for_compressor(n_bits, stcode, free_ent, extcode, maxbits);
+ 					}
+ 				}
+ 
+@@ -1518,8 +1532,7 @@ decompress(fdin, fdout)
+ 		maxmaxcode = MAXCODE(maxbits);
+ 
+ 		bytes_in = insize;
+-	    maxcode = MAXCODE(n_bits = INIT_BITS)-1;
+-		bitmask = (1<<n_bits)-1;
++		reset_n_bits_for_decompressor(n_bits, bitmask, maxbits, maxcode, maxmaxcode);
+ 		oldcode = -1;
+ 		finchar = 0;
+ 		outpos = 0;
+@@ -1598,8 +1611,7 @@ resetbuf:	;
+ 	    			free_ent = FIRST - 1;
+ 					posbits = ((posbits-1) + ((n_bits<<3) -
+ 								(posbits-1+(n_bits<<3))%(n_bits<<3)));
+-				    maxcode = MAXCODE(n_bits = INIT_BITS)-1;
+-					bitmask = (1<<n_bits)-1;
++					reset_n_bits_for_decompressor(n_bits, bitmask, maxbits, maxcode, maxmaxcode);
+ 					goto resetbuf;
+ 				}
+ 
+diff --git a/tests/runtests.sh b/tests/runtests.sh
+index 9a5bb99..f9c6e9a 100755
+--- a/tests/runtests.sh
++++ b/tests/runtests.sh
+@@ -174,4 +174,9 @@ uncompress -k i
+ [ -e i -a -e i.Z ]
+ rm i.Z
+ 
++: "### Check nine bits on large input"
++compress -b 9 <$COMPRESS >input.Z
++uncompress -c input.Z >input.new
++cmp $COMPRESS input.new
++
+ : "### All passed!"
+-- 
+2.43.0
+
diff --git a/ncompress.spec b/ncompress.spec
index a4410e2d35ebc68b47f55fdce6b0267f70f7e9cc..174d2a50bd59577bedccd2ea6613fe32c6785093 100644
--- a/ncompress.spec
+++ b/ncompress.spec
@@ -1,6 +1,6 @@
 Name:           ncompress
 Version:        5.0
-Release:        1
+Release:        2
 Summary:        A fast, simple LZW file compressor
 License:        Public Domain
 URL:            http://ncompress.sourceforge.net/
@@ -8,6 +8,8 @@ Source0:        https://github.com/vapier/%{name}/archive/v%{version}.tar.gz#/%{
 
 BuildRequires:	git gcc glibc-devel
 
+Patch0:         backport-fixed-nine-bits-processing-updated-reset-code-behavi.patch
+
 %description
 Compress is a fast, simple LZW file compressor. Compress does not have the highest
 compression rate, but it is one of the fastest programs to compress data. Compress
@@ -39,6 +41,9 @@ ln -sf compress.1 %{buildroot}%{_mandir}/man1/uncompress.1
 %{_mandir}/man1/*.gz
 
 %changelog
+* Wed Jul 30 2025 lijinlin <lijinlin@xfusion.com> -5.0-2
+- backport patch from upstream to fix nine bits decompression failed
+
 * Mon Jun 27 2022 dillon chen <dillon.chen@gmail.com> -5.0-1
 - update to 5.0