diff --git a/src/Makefile.am b/src/Makefile.am
index 090eb511..5f2f9d2c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -331,7 +331,8 @@ libmodsecurity_la_CPPFLAGS = \
 	$(SSDEEP_CFLAGS) \
 	$(MAXMIND_CFLAGS) \
 	$(LUA_CFLAGS) \
-	$(LIBXML2_CFLAGS)
+	$(LIBXML2_CFLAGS) \
+	$(CXX_FLAGS)
 
 
 libmodsecurity_la_LDFLAGS = \
diff --git a/tools/rules-check/Makefile.am b/tools/rules-check/Makefile.am
index 615d9598..248c5a56 100644
--- a/tools/rules-check/Makefile.am
+++ b/tools/rules-check/Makefile.am
@@ -34,7 +34,8 @@ modsec_rules_check_CPPFLAGS = \
 	$(PCRE_CFLAGS) \
 	$(LMDB_CFLAGS) \
 	$(MAXMIND_CFLAGS) \
-	$(LIBXML2_CFLAGS)
+	$(LIBXML2_CFLAGS) \
+	$(CXX_FLAGS)
 
 MAINTAINERCLEANFILES = \
         Makefile.in