Index: faxd/CopyQuality.c++
--- faxd/CopyQuality.c++.orig
+++ faxd/CopyQuality.c++
@@ -120,6 +120,11 @@ FaxModem::initializeDecoder(const Class2Params& params
 }
 
 /*
+ * Disable optimisation to avoid SIGABRT in G3Decoder.c++.
+ */
+#pragma clang optimize off
+
+/*
  * Receive Phase C data with or without copy
  * quality checking and erroneous row fixup.
  */
@@ -473,6 +478,11 @@ FaxModem::recvPageDLEData(TIFF* tif, bool checkQuality
     recvEndPage(tif, params);
     return (true);
 }
+
+/*
+ * Re-enable optimisation.
+ */
+#pragma clang optimize on
 
 /*
  * Setup "stock TIFF tags" in preparation for receiving a page of data.
