diff --git a/src/osdp_common.h b/src/osdp_common.h
index 9a4ce41..38f755b 100644
--- a/src/osdp_common.h
+++ b/src/osdp_common.h
@@ -81,9 +81,17 @@ static inline __noreturn void die()
 
 #define BUG() \
 	do { \
-		printf("BUG at %s:%d %s()", __FILE__, __LINE__, __func__); \
+		printf("BUG at %s:%d %s(). Please report this issue!", \
+		       __FILE__, __LINE__, __func__); \
 		die(); \
-	} while (0);
+	} while (0)
+
+#define BUG_ON(pred) \
+	do { \
+		if (unlikely(pred)) { \
+			BUG(); \
+		} \
+	} while (0)
 
 /* Unused type only to estimate ephemeral_data size */
 union osdp_ephemeral_data {
diff --git a/src/osdp_file.c b/src/osdp_file.c
index bdc7556..1e46151 100644
--- a/src/osdp_file.c
+++ b/src/osdp_file.c
@@ -33,15 +33,11 @@ int osdp_file_cmd_tx_build(struct osdp_pd *pd, uint8_t *buf, int max_len)
 	struct osdp_cmd_file_xfer *p = (struct osdp_cmd_file_xfer *)buf;
 	struct osdp_file *f = TO_FILE(pd);
 
-	if (f == NULL) {
-		LOG_ERR("TX_Build: File ops not registered!");
-		return -1;
-	}
-
-	if (f->state != OSDP_FILE_INPROG) {
-		LOG_ERR("TX_Build: File transfer is not in progress!");
-		return -1;
-	}
+	/**
+	 * We should never reach this function if a valid file transfer as in
+	 * progress.
+	 */
+	BUG_ON(f == NULL || f->state != OSDP_FILE_INPROG);
 
 	if ((size_t)max_len <= sizeof(struct osdp_cmd_file_xfer)) {
 		LOG_ERR("TX_Build: insufficient space need:%zu have:%d",
diff --git a/utils b/utils
index a096d8d..3de34d6 160000
--- a/utils
+++ b/utils
@@ -1 +1 @@
-Subproject commit a096d8d526be812f628183f3c181393b156c3651
+Subproject commit 3de34d6f2131f6e4ab837fc7d3f2dd20afcd7c1e