diff --git a/mie/print/op.c b/mie/print/op.c
index 5977684..95cd306 100644
--- a/mie/print/op.c
+++ b/mie/print/op.c
@@ -38,6 +38,10 @@ void mie_printer_print_op_arg(
 		b_stream_write_char(printer->p_stream, '%');
 	}
 
+	if (!arg_name) {
+		arg_name = "<NO-NAME>";
+	}
+
 	b_stream_write_string(printer->p_stream, arg_name, NULL);
 
 	if (!resolved
@@ -62,15 +66,20 @@ void mie_printer_print_op_successor(
 	b_stream_write_char(printer->p_stream, '^');
 	bool resolved = false;
 
+	const char *name = NULL;
 	if (successor->s_flags & MIE_OP_F_SUCCESSOR_RESOLVED) {
-		b_stream_write_string(
-			printer->p_stream, successor->s_block->b_name.n_str, NULL);
+		name = successor->s_block->b_name.n_str;
 		resolved = true;
 	} else {
-		b_stream_write_string(
-			printer->p_stream, successor->s_block_name, NULL);
+		name = successor->s_block_name;
 	}
 
+	if (!name) {
+		name = "<NO-NAME>";
+	}
+
+	b_stream_write_string(printer->p_stream, name, NULL);
+
 	if (!resolved
 	    && MIE_TEST_FLAGS(
 		    printer->p_flags, MIE_PRINT_F_MARK_UNRESOLVED_ELEMENTS)) {
diff --git a/mie/print/type.c b/mie/print/type.c
index bb5e60c..96fcef1 100644
--- a/mie/print/type.c
+++ b/mie/print/type.c
@@ -12,6 +12,11 @@
 
 void mie_printer_print_type(struct mie_printer *printer, const struct mie_type *type)
 {
+	if (!type) {
+		b_stream_write_string(printer->p_stream, "<NULL-TYPE>", NULL);
+		return;
+	}
+
 	if (TYPE_HAS_PRINT_CALLBACK(type)) {
 		type->ty_def->ty_print(type, printer);
 	} else if (TYPE_IS_BUILTIN(type)) {