diff --git a/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-c.cpp b/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-c.cpp
index b68ddd463..d5b20e9be 100644
--- a/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-c.cpp
+++ b/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-c.cpp
@@ -135,7 +135,8 @@ SyntaxDefinition& addObjectiveC() {
 			  { "byref", "keyword" },
 			  { "in", "keyword" },
 			  { "out", "keyword" },
-			  { "inout", "keyword" } },
+			  { "inout", "keyword" },
+			  { "readonly", "keyword" } },
 
 		  "//",
 		  {}
diff --git a/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-cpp.cpp b/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-cpp.cpp
index eff944faf..4f10b4eba 100644
--- a/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-cpp.cpp
+++ b/src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-cpp.cpp
@@ -219,7 +219,8 @@ SyntaxDefinition& addObjectiveCPP() {
 			  { "byref", "keyword" },
 			  { "in", "keyword" },
 			  { "out", "keyword" },
-			  { "inout", "keyword" } },
+			  { "inout", "keyword" },
+			  { "readonly", "keyword" } },
 
 		  "//",
 		  {},