diff --git a/README.md b/README.md
index ae3efa1..e5c0029 100644
--- a/README.md
+++ b/README.md
@@ -40,9 +40,9 @@ includes a JSON parser and emitter.
 
 While there are many excellent libraries out there that offer such capabilities for C++ and/or other object-oriented 
 languages, support for structured data exchange is notably rare for standard C. The __xchange__ library aims to fill 
-that niche, by providing a data exchange framework with a C90-compatible API that supports the interchange of 
+that niche, by providing a data exchange framework with a C99-compatible API that supports the interchange of 
 arbitrary structured data between different platforms and different serialization formats with ease. The __xchange__ 
-library also provides support for JSON formatting and parsing using the C90 standard out of the box. All that in a 
+library also provides support for JSON formatting and parsing using the C99 standard out of the box. All that in a 
 light-weight and fast package.
 
 The __xchange__ library was created, and is maintained, by Attila Kovács at the Center for Astrophysics \| Harvard 
diff --git a/resources/header.html b/resources/header.html
index 98d149e..7520224 100644
--- a/resources/header.html
+++ b/resources/header.html
@@ -6,7 +6,7 @@
 <meta http-equiv="X-UA-Compatible" content="IE=11"/>
 <meta charset="utf-8"/>
 <meta name="description" content="Structured data exchange for C/C++"/>
-<meta name="keywords" content="structured data, JSON, C, C++, C90, software library, open source"/>
+<meta name="keywords" content="structured data, JSON, C, C++, C99, software library, open source"/>
 <meta name="author" content="Attila Kovacs"/>
 <meta name="copyright" content="(C)2024 Attila Kovacs" />
 <meta name="robots" content="index,follow"/>