diff --git a/netpbm.changes b/netpbm.changes
index f6d3d11..edc492b 100644
--- a/netpbm.changes
+++ b/netpbm.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Sun Dec 19 17:47:53 UTC 2021 - Andreas Schwab <schwab@suse.de>
+
+- signed-char.patch: fix bad use of plain char
+
 -------------------------------------------------------------------
 Mon Dec 13 12:32:18 UTC 2021 - pgajdos@suse.com
 
diff --git a/netpbm.spec b/netpbm.spec
index ad6d962..606e889 100644
--- a/netpbm.spec
+++ b/netpbm.spec
@@ -41,6 +41,8 @@ Patch2:         %{name}-security-code.patch
 Patch3:         %{name}-security-scripts.patch
 Patch4:         %{name}-gcc-warnings.patch
 Patch5:         makeman-py3.patch
+# PATCH-FIX-UPSTREAM fix bad use of plain char
+Patch6:         signed-char.patch
 # PATCH-FIX-UPSTREAM fix dependency on byte order
 Patch7:         big-endian.patch
 # bsc#1144255 disable jpeg2k support due to removal of jasper
diff --git a/signed-char.patch b/signed-char.patch
new file mode 100644
index 0000000..727d74c
--- /dev/null
+++ b/signed-char.patch
@@ -0,0 +1,13 @@
+Index: netpbm-10.96.4/converter/other/pnmtopalm/palmtopnm.c
+===================================================================
+--- netpbm-10.96.4.orig/converter/other/pnmtopalm/palmtopnm.c
++++ netpbm-10.96.4/converter/other/pnmtopalm/palmtopnm.c
+@@ -873,7 +873,7 @@ readPackBitsRow(FILE *          const if
+         pm_readcharu(ifP, &incountByte);
+         if (incountByte & 0x80) {
+             /* How do we handle incount == -128 ? */
+-            int const signedIncount = (char)incountByte;
++            int const signedIncount = (signed char)incountByte;
+             unsigned int const runlength = -signedIncount + 1;
+             unsigned char inval;
+             pm_readcharu(ifP, &inval);