diff --git a/Makefile.am b/Makefile.am
index 6054461e222..3d130bdcbd7 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -84,7 +84,7 @@ bench_sign_SOURCES = src/bench_sign.c
 bench_sign_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB)
 bench_internal_SOURCES = src/bench_internal.c
 bench_internal_LDADD = $(SECP_LIBS) $(COMMON_LIB)
-bench_internal_CPPFLAGS = $(SECP_INCLUDES)
+bench_internal_CPPFLAGS = -DSECP256K1_BUILD $(SECP_INCLUDES)
 endif
 
 if USE_TESTS