diff --git a/Makefile b/Makefile
index 2c7eaaf..d901e46 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ ERLANG_PATH ?= $(shell erl -eval 'io:format("~s", [lists:concat([code:root_dir()
 CFLAGS += -I"$(ERLANG_PATH)"
 CFLAGS += -I c_src/secp256k1 -I c_src/secp256k1/src -I c_src/secp256k1/include
 CFLAGS += -I$(../libsecp256k1)/src
-SECP256K1_VERSION = v0.5.1
+SECP256K1_VERSION = v0.4.1
 
 ifneq ($(OS),Windows_NT)
 CFLAGS += -fPIC
diff --git a/c_src/libsecp256k1_nif.c b/c_src/libsecp256k1_nif.c
index d56af70..b95ac1e 100644
--- a/c_src/libsecp256k1_nif.c
+++ b/c_src/libsecp256k1_nif.c
@@ -139,7 +139,7 @@ rand32(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {
 	ERL_NIF_TERM r;
 	unsigned char* output = enif_make_new_binary(env, 4, &r);
-	uint32_t v = testrand32();
+	uint32_t v = secp256k1_testrand32();
     memcpy(&v, output, 4);
 	return r;
 }
@@ -149,7 +149,7 @@ rand256(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {
 	ERL_NIF_TERM r;
 	unsigned char* output = enif_make_new_binary(env, 32, &r);
-	testrand256(output);
+	secp256k1_testrand256(output);
 	return r;
 }