diff --git a/servers/rendering/shader_language.cpp b/servers/rendering/shader_language.cpp
index 9aa54d0bb775d6..b275cc4cb6e648 100644
--- a/servers/rendering/shader_language.cpp
+++ b/servers/rendering/shader_language.cpp
@@ -3085,6 +3085,19 @@ const ShaderLanguage::BuiltinFuncConstArgs ShaderLanguage::builtin_func_const_ar
 	{ nullptr, 0, 0, 0 }
 };
 
+const ShaderLanguage::BuiltinFuncFragLight ShaderLanguage::builtin_func_fragment_light_only[] = {
+	{ "dFdx" },
+	{ "dFdxCoarse" },
+	{ "dFdxFine" },
+	{ "dFdy" },
+	{ "dFdyCoarse" },
+	{ "dFdyFine" },
+	{ "fwidth" },
+	{ "fwidthCoarse" },
+	{ "fwidthFine" },
+	{ nullptr }
+};
+
 bool ShaderLanguage::is_const_suffix_lut_initialized = false;
 
 bool ShaderLanguage::_validate_function_call(BlockNode *p_block, const FunctionInfo &p_function_info, OperatorNode *p_func, DataType *r_ret_type, StringName *r_ret_type_str, bool *r_is_custom_function) {
@@ -3137,6 +3150,7 @@ bool ShaderLanguage::_validate_function_call(BlockNode *p_block, const FunctionI
 	if (argcount <= 4) {
 		// test builtins
 		int idx = 0;
+		bool is_non_frag_light = current_function != "fragment" && current_function != "light";
 
 		while (builtin_func_defs[idx].name) {
 			if (completion_class != builtin_func_defs[idx].tag) {
@@ -3178,6 +3192,16 @@ bool ShaderLanguage::_validate_function_call(BlockNode *p_block, const FunctionI
 				}
 
 				if (!fail) {
+					if (is_non_frag_light) {
+						int idx2 = 0;
+						while (builtin_func_fragment_light_only[idx2].name) {
+							if (name == builtin_func_fragment_light_only[arg_idx].name) {
+								_set_error(vformat(RTR("'%s' cannot be used outside of the '%s' or '%s' processor functions."), String(name), "fragment", "light"));
+								return false;
+							}
+							idx2++;
+						}
+					}
 					{
 						int constarg_idx = 0;
 						while (builtin_func_const_args[constarg_idx].name) {
@@ -10324,11 +10348,33 @@ Error ShaderLanguage::complete(const String &p_code, const ShaderCompileInfo &p_
 					}
 				}
 
+				bool is_non_frag_light = current_function != "fragment" && current_function != "light";
+
 				while (builtin_func_defs[idx].name) {
 					if (low_end && builtin_func_defs[idx].high_end) {
 						idx++;
 						continue;
 					}
+
+					if (is_non_frag_light) {
+						bool found = false;
+						{
+							int idx2 = 0;
+							while (builtin_func_fragment_light_only[idx2].name) {
+								if (String(builtin_func_fragment_light_only[idx2].name) == builtin_func_defs[idx].name) {
+									found = true;
+									break;
+								}
+								idx2++;
+							}
+						}
+
+						if (found) {
+							idx++;
+							continue;
+						}
+					}
+
 					matches.insert(String(builtin_func_defs[idx].name), ScriptLanguage::CODE_COMPLETION_KIND_FUNCTION);
 					idx++;
 				}
@@ -10498,7 +10544,7 @@ Error ShaderLanguage::complete(const String &p_code, const ShaderCompileInfo &p_
 				int idx2 = 0;
 				HashSet<int> out_args;
 				while (builtin_func_out_args[idx2].name != nullptr) {
-					if (builtin_func_out_args[idx2].name == builtin_func_defs[idx].name) {
+					if (String(builtin_func_out_args[idx2].name) == builtin_func_defs[idx].name) {
 						for (int i = 0; i < BuiltinFuncOutArgs::MAX_ARGS; i++) {
 							int arg = builtin_func_out_args[idx2].arguments[i];
 							if (arg == -1) {
diff --git a/servers/rendering/shader_language.h b/servers/rendering/shader_language.h
index 5615d7f457fdeb..31e3071202695f 100644
--- a/servers/rendering/shader_language.h
+++ b/servers/rendering/shader_language.h
@@ -1059,6 +1059,10 @@ class ShaderLanguage {
 		int max;
 	};
 
+	struct BuiltinFuncFragLight {
+		const char *name;
+	};
+
 	CompletionType completion_type;
 	ShaderNode::Uniform::Hint current_uniform_hint = ShaderNode::Uniform::HINT_NONE;
 	TextureFilter current_uniform_filter = FILTER_DEFAULT;
@@ -1083,6 +1087,7 @@ class ShaderLanguage {
 	static const BuiltinFuncDef builtin_func_defs[];
 	static const BuiltinFuncOutArgs builtin_func_out_args[];
 	static const BuiltinFuncConstArgs builtin_func_const_args[];
+	static const BuiltinFuncFragLight builtin_func_fragment_light_only[];
 
 	static bool is_const_suffix_lut_initialized;