diff --git a/components/prism-c.js b/components/prism-c.js
index a9525d4024..ad2cf999f2 100644
--- a/components/prism-c.js
+++ b/components/prism-c.js
@@ -1,5 +1,5 @@
 Prism.languages.c = Prism.languages.extend('clike', {
-	'keyword': /\b(asm|typeof|inline|auto|break|case|char|const|continue|default|do|double|else|enum|extern|float|for|goto|if|int|long|register|return|short|signed|sizeof|static|struct|switch|typedef|union|unsigned|void|volatile|while)\b/,
+	'keyword': /\b(_Alignas|_Alignof|_Atomic|_Bool|_Complex|_Generic|_Imaginary|_Noreturn|_Static_assert|_Thread_local|asm|typeof|inline|auto|break|case|char|const|continue|default|do|double|else|enum|extern|float|for|goto|if|int|long|register|return|short|signed|sizeof|static|struct|switch|typedef|union|unsigned|void|volatile|while)\b/,
 	'operator': /\-[>-]?|\+\+?|!=?|<<?=?|>>?=?|==?|&&?|\|?\||[~^%?*\/]/,
 	'number': /\b-?(?:0x[\da-f]+|\d*\.?\d+(?:e[+-]?\d+)?)[ful]*\b/i
 });
@@ -19,14 +19,14 @@ Prism.languages.insertBefore('c', 'string', {
 			},
 			// highlight macro directives as keywords
 			'directive': {
-				pattern: /(#\s*)\b(define|elif|else|endif|error|ifdef|ifndef|if|import|include|line|pragma|undef|using)\b/,
+				pattern: /(#\s*)\b(define|defined|elif|else|endif|error|ifdef|ifndef|if|import|include|line|pragma|undef|using)\b/,
 				lookbehind: true,
 				alias: 'keyword'
 			}
 		}
 	},
 	// highlight predefined macros as constants
-	'constant': /\b(__FILE__|__LINE__|__DATE__|__TIME__|__TIMESTAMP__|__func__|EOF|NULL|stdin|stdout|stderr)\b/
+	'constant': /\b(__FILE__|__LINE__|__DATE__|__TIME__|__TIMESTAMP__|__func__|EOF|NULL|SEEK_CUR|SEEK_END|SEEK_SET|stdin|stdout|stderr)\b/
 });
 
 delete Prism.languages.c['class-name'];