diff --git a/syntaxes/classicalb.tmLanguage.json b/syntaxes/classicalb.tmLanguage.json
index 2cfef9a4c81519f62dda6a19a8a8aebe37e67c09..084029cfc6676a88b008672bcc5038b5895350f7 100644
--- a/syntaxes/classicalb.tmLanguage.json
+++ b/syntaxes/classicalb.tmLanguage.json
@@ -278,7 +278,7 @@
 	  "control_blocks": {
 		"patterns": [
 		  {
-			"begin": "(?x)\n\\b(BEGIN|PRE|SELECT|ANY|LET|VAR|ASSERT|WHILE|IF|CHOICE|CASE|EITHER)\\b",
+			"begin": "(?x)\n\\b(BEGIN|PRE|SELECT|WITNESS|ANY|LET|VAR|ASSERT|WHILE|IF|CHOICE|CASE|EITHER)\\b",
 			"beginCaptures": {
 			  "0": {
 				"name": "keyword.control.classicalb"
diff --git a/syntaxes/rmchAddOn.tmLanguage.json b/syntaxes/rmchAddOn.tmLanguage.json
index eb732c26f608dc1964803f914f205ba88a3135a7..85cb522e00887d52a26c1613628df2e626b01c9f 100644
--- a/syntaxes/rmchAddOn.tmLanguage.json
+++ b/syntaxes/rmchAddOn.tmLanguage.json
@@ -284,7 +284,7 @@
 	  "control_blocks": {
 		"patterns": [
 		  {
-			"begin": "(?x)\n\\b(BEGIN|PRE|SELECT|ANY|LET|VAR|ASSERT|WHILE|FOR|DO|IF|CHOICE|CASE|EITHER|IN)\\b",
+			"begin": "(?x)\n\\b(BEGIN|PRE|SELECT|WITNESS|ANY|LET|VAR|ASSERT|WHILE|FOR|DO|IF|CHOICE|CASE|EITHER|IN)\\b",
 			"beginCaptures": {
 			  "0": {
 				"name": "keyword.control.rmchAddOn"