diff --git a/src/libImaging/Jpeg2KEncode.c b/src/libImaging/Jpeg2KEncode.c
index 5829cf37f..2e6b5daf0 100644
--- a/src/libImaging/Jpeg2KEncode.c
+++ b/src/libImaging/Jpeg2KEncode.c
@@ -385,7 +385,7 @@ j2k_encode_entry(Imaging im, ImagingCodecState state) {
         float *pq;
 
         if (len > 0) {
-            if ((unsigned)len >
+            if ((size_t)len >
                 sizeof(params.tcp_rates) / sizeof(params.tcp_rates[0])) {
                 len = sizeof(params.tcp_rates) / sizeof(params.tcp_rates[0]);
             }