diff --git a/src/cc/cclib.cpp b/src/cc/cclib.cpp
index 7fb06259a..e6b405955 100644
--- a/src/cc/cclib.cpp
+++ b/src/cc/cclib.cpp
@@ -609,11 +609,11 @@ struct secp256k1_context_struct {
 };
 
 typedef int (secp256k1_ecmult_multi_callback)(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data);
-void secp256k1_pubkey_save(secp256k1_pubkey* pubkey, secp256k1_ge* ge);
-int secp256k1_nonce_function_bipschnorr(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *algo16, void *data, unsigned int counter);
+extern "C" void secp256k1_pubkey_save(secp256k1_pubkey* pubkey, secp256k1_ge* ge);
+extern "C" int secp256k1_nonce_function_bipschnorr(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *algo16, void *data, unsigned int counter);
 extern "C" int secp256k1_pubkey_load(const secp256k1_context* ctx, secp256k1_ge* ge, const secp256k1_pubkey* pubkey);
-void secp256k1_scalar_chacha20(secp256k1_scalar *r1, secp256k1_scalar *r2, const unsigned char *seed, uint64_t idx);
-int secp256k1_ecmult_multi_var(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n);
+extern "C" void secp256k1_scalar_chacha20(secp256k1_scalar *r1, secp256k1_scalar *r2, const unsigned char *seed, uint64_t idx);
+extern "C" int secp256k1_ecmult_multi_var(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n);
 
 #define ARG_CHECK(cond) do { \
 if (EXPECT(!(cond), 0)) { \