diff --git a/README.md b/README.md
index 2cc5626..63c2c8c 100644
--- a/README.md
+++ b/README.md
@@ -88,7 +88,7 @@ consteval double parse(std::string_view input) {
 
 // This function should compile to a function which
 // merely returns 3.1415.
-double constexptest() {
+constexpr double constexptest() {
   return parse("3.1415 input");
 }
 ```
diff --git a/tests/example_test.cpp b/tests/example_test.cpp
index cb9be38..91437de 100644
--- a/tests/example_test.cpp
+++ b/tests/example_test.cpp
@@ -54,7 +54,7 @@ consteval double parse(std::string_view input) {
 
 // This function should compile to a function which
 // merely returns 3.1415.
-double constexptest() {
+constexpr double constexptest() {
   return parse("3.1415 input");
 }
 #endif