diff --git a/servers/visual/shader_language.cpp b/servers/visual/shader_language.cpp
index a042640a5df..c1759251ed5 100644
--- a/servers/visual/shader_language.cpp
+++ b/servers/visual/shader_language.cpp
@@ -5620,7 +5620,7 @@ Error ShaderLanguage::_parse_shader(const Map<StringName, FunctionInfo> &p_funct
 				st.shader_struct = st_node;
 
 				int member_count = 0;
-
+				Set<String> member_names;
 				while (true) { // variables list
 					tk = _get_token();
 					if (tk.type == TK_CURLY_BRACKET_CLOSE) {
@@ -5677,6 +5677,12 @@ Error ShaderLanguage::_parse_shader(const Map<StringName, FunctionInfo> &p_funct
 						member->struct_name = struct_name;
 						member->name = tk.text;
 
+						if (member_names.has(member->name)) {
+							_set_error("Redefinition of '" + String(member->name) + "'");
+							return ERR_PARSE_ERROR;
+						}
+						member_names.insert(member->name);
+
 						tk = _get_token();
 						if (tk.type == TK_BRACKET_OPEN) {
 							tk = _get_token();