diff --git a/receiver/JFJochReceiverFPGA.cpp b/receiver/JFJochReceiverFPGA.cpp
index 5ba633b2..5d8aa6cc 100644
--- a/receiver/JFJochReceiverFPGA.cpp
+++ b/receiver/JFJochReceiverFPGA.cpp
@@ -479,9 +479,15 @@ void JFJochReceiverFPGA::FrameTransformationThread(uint32_t threadid) {
 
                     const auto compression_start_time = std::chrono::steady_clock::now();
                     try {
+                        // Reserve 32 bytes for close, etc. If the metadata already fills the
+                        // slot the subtraction below would wrap (size_t), so bail out here and
+                        // let the catch drop just this frame.
+                        if (metadata_size + 32 >= slot_size)
+                            throw CompressionBufferTooSmallException("CBOR metadata leaves no room for the compressed image");
+
                         size_t image_size = transformation.CompressImage(
                                 writer_buffer + serializer.GetImageAppendOffset(),
-                                slot_size - (metadata_size + 32)); // keep 32 byte extra for close, etc.
+                                slot_size - (metadata_size + 32));
                         const auto compression_end_time = std::chrono::steady_clock::now();
                         message.compression_time_s = std::chrono::duration<float>(
                             compression_end_time - compression_start_time).count();