diff --git a/lib/std/io/formatter.c3 b/lib/std/io/formatter.c3
index dc408dc4a..bbbdce3c5 100644
--- a/lib/std/io/formatter.c3
+++ b/lib/std/io/formatter.c3
@@ -147,11 +147,13 @@ fn usz? Formatter.out_str(&self, any arg) @private
 			return self.out_substr("void");
 		case FAULT:
 			fault f = *(fault*)arg.ptr;
-			return self.out_substr(f ? f.nameof : "(nofault)");
+			return self.out_substr(f ? f.nameof : "(empty-fault)");
 		case INTERFACE:
+			any a = *(any*)arg;
+			return a ? self.out_str(a) : self.out_substr("(empty-interface)");
 		case ANY:
 			any a = *(any*)arg;
-			return a ? self.out_str(a) : self.out_substr("(null)");
+			return a ? self.out_str(a) : self.out_substr("(empty-any)");
 		case OPTIONAL:
 			unreachable();
 		case SIGNED_INT:
diff --git a/test/unit/regression/formatting.c3 b/test/unit/regression/formatting.c3
index 89300e509..5608fc317 100644
--- a/test/unit/regression/formatting.c3
+++ b/test/unit/regression/formatting.c3
@@ -20,10 +20,13 @@ fn void various_cornercases() @test
     test::eq(string::tformat("%s", z), "[100]");
 
     fault p; fault o = DERP;
-    test::eq(string::tformat("%s|%s", p, o), "(nofault)|format_test::DERP");
+    test::eq(string::tformat("%s|%s", p, o), "(empty-fault)|format_test::DERP");
 
     Decl y;
-    test::eq(string::tformat("%s", y), "(null)");
+    test::eq(string::tformat("%s", y), "(empty-interface)");
+
+    any xx;
+    test::eq(string::tformat("%s", xx), "(empty-any)");
 
     int* x;
     test::eq(string::tformat("%s", x), "0x0");