diff --git a/tests/gsm0808/gsm0808_test.c b/tests/gsm0808/gsm0808_test.c
index a9ab72b..49673fe 100644
--- a/tests/gsm0808/gsm0808_test.c
+++ b/tests/gsm0808/gsm0808_test.c
@@ -595,17 +595,17 @@
 
 static void test_gsm0808_enc_dec_speech_codec_with_cfg()
 {
-	struct gsm0808_speech_codec enc_sc;
-	struct gsm0808_speech_codec dec_sc;
+	struct gsm0808_speech_codec enc_sc = {
+		.pi = true,
+		.tf = true,
+		.type = GSM0808_SCT_FR3,
+		.cfg = 0xabcd,
+	};
+	struct gsm0808_speech_codec dec_sc = {};
 	struct msgb *msg;
 	uint8_t rc_enc;
 	int rc_dec;
 
-	enc_sc.pi = true;
-	enc_sc.tf = true;
-	enc_sc.type = GSM0808_SCT_FR3;
-	enc_sc.cfg = 0xabcd;
-
 	msg = msgb_alloc(1024, "output buffer");
 	rc_enc = gsm0808_enc_speech_codec(msg, &enc_sc);
 	OSMO_ASSERT(rc_enc == 5);