diff --git a/third-party/pjproject/Makefile.rules b/third-party/pjproject/Makefile.rules
index f6790bd216..d09da39817 100644
--- a/third-party/pjproject/Makefile.rules
+++ b/third-party/pjproject/Makefile.rules
@@ -50,4 +50,4 @@ ifeq ($(shell uname -s),Linux)
     PJPROJECT_CFLAGS += -DPJ_HAS_LINUX_EPOLL=1
 endif
 
-PJPROJECT_CONFIG_OPTS += CFLAGS="$(PJPROJECT_CFLAGS)"
+PJPROJECT_CONFIG_OPTS += CFLAGS="$(CFLAGS) $(PJPROJECT_CFLAGS)"