diff --git a/src/shearwater_petrel.c b/src/shearwater_petrel.c
index 67a3bbc..f71a89f 100644
--- a/src/shearwater_petrel.c
+++ b/src/shearwater_petrel.c
@@ -263,25 +263,27 @@ shearwater_petrel_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 		return rc;
 	}
 	unsigned int base_addr = array_uint_be (dc_buffer_get_data (buffer), dc_buffer_get_size (buffer));
+	INFO(abstract->context, "RDBI command completed with %d bytes, evaluated as %08x", dc_buffer_get_size (buffer), base_addr);
 	base_addr &= 0xFF000000u;
 	switch (base_addr) {
 	case 0xDD000000: // Predator or Predator-Like Format
 		// on a Predator, use the old format, otherwise use the Predator-Like Format (what we called Petrel so far)
 		if (model != PREDATOR)
-			base_addr = 0xC0000000;
+			base_addr = 0xC0000000u;
 		break;
 	case 0x90000000: // some firmware versions supported an earlier version of PNF without final record
 		// use the Predator-Like Format instead
-		base_addr = 0xC0000000;
+		base_addr = 0xC0000000u;
 		break;
 	case 0x80000000: // new Petrel Native Format with final record
 		// that's the correct address
 		break;
 	default: // unknown format
-		ERROR (abstract->context, "Unknown logbook format %08x", base_addr);
-		dc_buffer_free (buffer);
-		dc_buffer_free (manifests);
-		return DC_STATUS_UNSUPPORTED;
+		// use the defaults for the models
+		if (model >= TERIC)
+			base_addr = 0x80000000u;
+		else
+			base_addr = 0xC0000000u;
 	}
 
 	// Read the manifest pages