diff --git a/src/Makefile.am b/src/Makefile.am
index 0ed412295..ffa2980d5 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -309,7 +309,7 @@ libbitcoin_server_a_SOURCES += dummywallet.cpp
 endif
 
 if ENABLE_ZMQ
-libbitcoin_zmq_a_CPPFLAGS = $(BITCOIN_INCLUDES) $(ZMQ_CFLAGS)
+libbitcoin_zmq_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(ZMQ_CFLAGS)
 libbitcoin_zmq_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_zmq_a_SOURCES = \
   zmq/zmqabstractnotifier.cpp \