diff --git a/CppCoreGuidelines.md b/CppCoreGuidelines.md
index e3b2c1d..cc73cfe 100644
--- a/CppCoreGuidelines.md
+++ b/CppCoreGuidelines.md
@@ -13319,7 +13319,7 @@ The less sharing you do, the less chance you have to wait on a lock (so performa
     Image altitude_map(const vector<Reading>&);
     // ...
 
-    void process_readings(const vector<Readings>& surface_readings)
+    void process_readings(const vector<Reading>& surface_readings)
     {
         auto h1 = async([&] { if (!validate(surface_readings)) throw Invalid_data{}; });
         auto h2 = async([&] { return temperature_gradiants(surface_readings); });