diff --git a/src/Makefile.am b/src/Makefile.am
index 63a690d49f..7cd85ce6a8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -672,7 +672,7 @@ endif
 #
 
 # util #
-libbitcoin_util_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS)
+libbitcoin_util_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_util_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_util_a_SOURCES = \
   support/lockedpool.cpp \