--- afdko/c/addfeatures/cb.h
+++ afdko/c/addfeatures/cb.h
@@ -19,7 +19,8 @@
 
 /* --- Basic functions --- */
 cbCtx cbNew(const char *progname, const char *indir, const char *outdir,
-            const char *cmapdir, const char *featdir, dnaCtx mainDnaCtx);
+            const char *cmapdir, const char *featdir, dnaCtx mainDnaCtx,
+            void (*fatal)(void *ctx));
 void cbConvert(cbCtx h, int flags, const char *clientVers,
                const char *infile, const char *outfile,
                const char *featurefile, const char *hcmapfile,
--- afdko/c/addfeatures/cb.cpp
+++ afdko/c/addfeatures/cb.cpp
@@ -91,6 +91,7 @@
     std::shared_ptr<GOADB> goadb;
     std::shared_ptr<Designspace> ds;
     std::shared_ptr<slogger> logger;
+    void (*clientFatal)(void *ctx) = NULL; /* Called by myfatal() in place of process exit. Must not return. */
 };
 
 /* ----------------------------- Error Handling ---------------------------- */
@@ -98,6 +99,8 @@
 /* Fatal exception handler */
 static void myfatal(void *ctx) {
     cbCtx h = (cbCtx) ctx;
+    if (h->clientFatal != NULL)
+        h->clientFatal(ctx);
     /*This seems to cause all kinds of crashes on Windows and OSX*/
     /* hotFree(h->hot.ctx);*/ /* Free library context */
 
@@ -468,9 +471,12 @@
 
 /* Create new callback context */
 cbCtx cbNew(const char *progname, const char *indir, const char *outdir,
-            const char *cmapdir, const char *featdir, dnaCtx mainDnaCtx) {
+            const char *cmapdir, const char *featdir, dnaCtx mainDnaCtx,
+            void (*fatal)(void *ctx)) {
     cbCtx h = new cbCtx_;
 
+    h->clientFatal = fatal;
+
     hotcbInit(h);
 
     stmClear(&h->in);
@@ -808,3 +814,12 @@
 
     delete h;
 }
+
+/* Defined in main.cpp upstream, which is not compiled here. */
+extern "C" const char *curdir() {
+    return ".";
+}
+
+extern "C" const char *sep() {
+    return "/";
+}
--- afdko/c/addfeatures/pstoken/pstoken.c
+++ afdko/c/addfeatures/pstoken/pstoken.c
@@ -7,7 +7,7 @@
  */
 
 #include <stdint.h>
-#include "pstoken.h"
+#include "../include/pstoken.h"
 
 #include <stdarg.h>
 #include <stdlib.h>
--- afdko/c/addfeatures/hotconv/map.cpp
+++ afdko/c/addfeatures/hotconv/map.cpp
@@ -23,7 +23,7 @@
 #include "otl.h"
 #include "FeatCtx.h"
 
-#include "pstoken.h"
+#include "../include/pstoken.h"
 
 #define SET_BIT_ARR(a, b) (a[(b) / 32] |= 1UL << (b) % 32)
 #define TEST_BIT_ARR(a, b) (a[(b) / 32] & 1UL << (b) % 32)