diff --git a/src/core/Associative.pm b/src/core/Associative.pm
index 40aa6b06ca1..2d5874d885e 100644
--- a/src/core/Associative.pm
+++ b/src/core/Associative.pm
@@ -1,2 +1,3 @@
-my role Associative {
+my role Associative[::T = Mu] {
+    method of() { T }
 }
diff --git a/src/core/Callable.pm b/src/core/Callable.pm
index 5fde242fbc8..58df49c19f6 100644
--- a/src/core/Callable.pm
+++ b/src/core/Callable.pm
@@ -1,2 +1,4 @@
-my role Callable {
+my role Callable[::T = Mu] {
+    method of() { T }
+    method returns() { T }
 }
diff --git a/src/core/Positional.pm b/src/core/Positional.pm
index 3f584fa5c15..ac73982c0eb 100644
--- a/src/core/Positional.pm
+++ b/src/core/Positional.pm
@@ -1,2 +1,3 @@
-my role Positional {
+my role Positional[::T = Mu] {
+    method of() { T }
 }