--- afdko/c/shared/include/tx_shared.h
+++ afdko/c/shared/include/tx_shared.h
@@ -288,6 +288,7 @@
     int mode;                         /* Current mode */
     const char *modename;             /* Name of current mode */
     txExtCtx ext;                     /* Extension context (if any) */
+    void (*fatalCallback)(struct txCtx_ *h); /* Called by fatal() in place of process exit. Must not return. */
     abfTopDict *top;                  /* Top dictionary */
     struct {                          /* Source data */
         int type;                        /* Font technology type */
--- afdko/c/shared/tx_shared.cpp
+++ afdko/c/shared/tx_shared.cpp
@@ -33,6 +33,8 @@
     } else {
         h->logger->msg(sFATAL, "fatal error");
     }
+    if (h->fatalCallback != NULL)
+        h->fatalCallback(h);
     txFree(h);
     exit(EXIT_FAILURE);
 }