--- Firebird-4.0.0.2496-0/examples/extauth/Makefile.orig	2021-05-29 10:05:05.000000000 -0500
+++ Firebird-4.0.0.2496-0/examples/extauth/Makefile	2021-08-12 23:18:51.773913508 -0500
@@ -61,7 +61,7 @@
 TCWRAP_objects=$(INTERMED)/TcWrapper.o
 KEY_AUTH_objects=$(INTERMED)/ExtAuth.o
 
-CXXFLAGS=-std=c++11 -pthread -I$(ROOT)/include -fPIC $(TOMCRYPT_COMPILE)
+CXXFLAGS=-std=c++11 -pthread -I$(ROOT)/include -I$(ROOT)/src/include -fPIC $(TOMCRYPT_COMPILE)
 LDFLAGS=-pthread -L$(LIB) -Wl,-rpath,'$$ORIGIN/../lib' $(TOMCRYPT_LINK)
 
 LINK_LIBS=-lfbclient -ltomcrypt -ltommath