diff --git a/third_party/libopenjpeg20/0011-j2k_update_image_data.patch b/third_party/libopenjpeg20/0011-j2k_update_image_data.patch
new file mode 100644
index 0000000..697c48f
--- /dev/null
+++ b/third_party/libopenjpeg20/0011-j2k_update_image_data.patch
@@ -0,0 +1,17 @@
+diff --git a/third_party/libopenjpeg20/j2k.c b/third_party/libopenjpeg20/j2k.c
+index b20f219..9056feb 100644
+--- a/third_party/libopenjpeg20/j2k.c
++++ b/third_party/libopenjpeg20/j2k.c
+@@ -8211,6 +8211,12 @@ static OPJ_BOOL opj_j2k_update_image_data (opj_tcd_t * p_tcd, OPJ_BYTE * p_data,
+                  * */
+                 assert( l_res->x0 >= 0);
+                 assert( l_res->x1 >= 0);
++
++                /* Prevent bad casting to unsigned values in the subsequent lines. */
++                if ( l_res->x0 < 0 || l_res->x1 < 0 || l_res->y0 < 0 || l_res->y1 < 0 ) {
++                        return OPJ_FALSE;
++                }
++
+                 if ( l_x0_dest < (OPJ_UINT32)l_res->x0 ) {
+                         l_start_x_dest = (OPJ_UINT32)l_res->x0 - l_x0_dest;
+                         l_offset_x0_src = 0;
diff --git a/third_party/libopenjpeg20/README.pdfium b/third_party/libopenjpeg20/README.pdfium
index c4d8976..0a60ed7 100644
--- a/third_party/libopenjpeg20/README.pdfium
+++ b/third_party/libopenjpeg20/README.pdfium
@@ -20,4 +20,5 @@
 0008-jp2_check_color.patch: Replace an assertion with returning false.
 0009-opj_pi_next.patch: Fix potential bad precno value in opj_pi_next* functions.
 0010-pi_update_decode_poc.patch: Set proper upper bound for an array in opj_pi_update_decode_poc().
+0011-j2k_update_image_data.patch: Prevent bad signed -> unsigned casting.
 TODO(thestig): List all the other patches.
diff --git a/third_party/libopenjpeg20/j2k.c b/third_party/libopenjpeg20/j2k.c
index b20f219..9056feb 100644
--- a/third_party/libopenjpeg20/j2k.c
+++ b/third_party/libopenjpeg20/j2k.c
@@ -8211,6 +8211,12 @@
                  * */
                 assert( l_res->x0 >= 0);
                 assert( l_res->x1 >= 0);
+
+                /* Prevent bad casting to unsigned values in the subsequent lines. */
+                if ( l_res->x0 < 0 || l_res->x1 < 0 || l_res->y0 < 0 || l_res->y1 < 0 ) {
+                        return OPJ_FALSE;
+                }
+
                 if ( l_x0_dest < (OPJ_UINT32)l_res->x0 ) {
                         l_start_x_dest = (OPJ_UINT32)l_res->x0 - l_x0_dest;
                         l_offset_x0_src = 0;