diff --git a/builds/posix/Makefile.in.plugins_examples b/builds/posix/Makefile.in.plugins_examples
index 625f37b28c..69809dd0fb 100644
--- a/builds/posix/Makefile.in.plugins_examples
+++ b/builds/posix/Makefile.in.plugins_examples
@@ -29,7 +29,7 @@
 #
 ROOT=../..
 
-CXXFLAGS+= -I$(FIREBIRD)/include
+CPPFLAGS+= -I$(FIREBIRD)/include
 
 include     $(ROOT)/gen/make.defaults
 include     $(ROOT)/gen/make.platform
diff --git a/builds/posix/make.rules b/builds/posix/make.rules
index 60fb075c6a..7293eafe61 100644
--- a/builds/posix/make.rules
+++ b/builds/posix/make.rules
@@ -32,7 +32,7 @@
 
 
 # Please don't use compiler/platform specific flags here - nmcc 02-Nov-2002
-WFLAGS:=-I$(SRC_ROOT)/include/gen -I$(SRC_ROOT)/include
+WFLAGS:=-I$(SRC_ROOT)/include/gen -I$(SRC_ROOT)/include $(CPPFLAGS)
 
 ifeq ($(TARGET),Release)
   WFLAGS:= $(PROD_FLAGS) $(WFLAGS)