diff --git a/Makefile.am b/Makefile.am
index 6054461e..3d130bdc 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
diff --git a/src/field_10x26_impl.h b/src/field_10x26_impl.h
index a8188b4a..7b8c0796 100644
--- a/src/field_10x26_impl.h
+++ b/src/field_10x26_impl.h
@@ -7,8 +7,6 @@
 #ifndef _SECP256K1_FIELD_REPR_IMPL_H_
 #define _SECP256K1_FIELD_REPR_IMPL_H_
 
-#include <stdio.h>
-#include <string.h>
 #include "util.h"
 #include "num.h"
 #include "field.h"
diff --git a/src/field_5x52_impl.h b/src/field_5x52_impl.h
index b31e24ab..7a99eb21 100644
--- a/src/field_5x52_impl.h
+++ b/src/field_5x52_impl.h
@@ -11,7 +11,6 @@
 #include "libsecp256k1-config.h"
 #endif
 
-#include <string.h>
 #include "util.h"
 #include "num.h"
 #include "field.h"
diff --git a/src/group_impl.h b/src/group_impl.h
index f9036854..8357b4b1 100644
--- a/src/group_impl.h
+++ b/src/group_impl.h
@@ -7,8 +7,6 @@
 #ifndef _SECP256K1_GROUP_IMPL_H_
 #define _SECP256K1_GROUP_IMPL_H_
 
-#include <string.h>
-
 #include "num.h"
 #include "field.h"
 #include "group.h"
diff --git a/src/scalar_impl.h b/src/scalar_impl.h
index 88ea97de..c5baf4df 100644
--- a/src/scalar_impl.h
+++ b/src/scalar_impl.h
@@ -7,8 +7,6 @@
 #ifndef _SECP256K1_SCALAR_IMPL_H_
 #define _SECP256K1_SCALAR_IMPL_H_
 
-#include <string.h>
-
 #include "group.h"
 #include "scalar.h"