diff --git a/src/ArduinoJson/Strings/Adapters/RamString.hpp b/src/ArduinoJson/Strings/Adapters/RamString.hpp
index 6d7d68ed..deb09980 100644
--- a/src/ArduinoJson/Strings/Adapters/RamString.hpp
+++ b/src/ArduinoJson/Strings/Adapters/RamString.hpp
@@ -90,8 +90,9 @@ struct StringAdapter<TChar[N], enable_if_t<IsChar<TChar>::value>> {
   using AdaptedString = RamString;
 
   static AdaptedString adapt(const TChar* p) {
+    ARDUINOJSON_ASSERT(p);
     auto str = reinterpret_cast<const char*>(p);
-    return AdaptedString(str, str ? ::strlen(str) : 0);
+    return AdaptedString(str, ::strlen(str));
   }
 };