diff --git a/src/conv.c b/src/conv.c
index a2c13de..06c4299 100644
--- a/src/conv.c
+++ b/src/conv.c
@@ -36,6 +36,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <osmocom/core/utils.h>
 #include <osmocom/core/bits.h>
 #include <osmocom/core/conv.h>
 
@@ -87,6 +88,7 @@
                       const struct osmo_conv_code *code)
 {
 	memset(encoder, 0x00, sizeof(struct osmo_conv_encoder));
+	OSMO_ASSERT(code != NULL);
 	encoder->code = code;
 }