diff --git a/CPP20.md b/CPP20.md
index 764c770..f6bc070 100644
--- a/CPP20.md
+++ b/CPP20.md
@@ -321,7 +321,7 @@ struct foo {
   constexpr foo(int) {}
 };
 
-template <foo f>
+template <foo f = {}>
 auto get_foo() {
   return f;
 }
diff --git a/README.md b/README.md
index 143d01f..a5f2ee4 100644
--- a/README.md
+++ b/README.md
@@ -424,7 +424,7 @@ struct foo {
   constexpr foo(int) {}
 };
 
-template <foo f>
+template <foo f = {}>
 auto get_foo() {
   return f;
 }