diff --git a/3rdparty/glsl-optimizer/src/glsl/ir_print_metal_visitor.cpp b/3rdparty/glsl-optimizer/src/glsl/ir_print_metal_visitor.cpp
index f9988a31f..9f7071d95 100644
--- a/3rdparty/glsl-optimizer/src/glsl/ir_print_metal_visitor.cpp
+++ b/3rdparty/glsl-optimizer/src/glsl/ir_print_metal_visitor.cpp
@@ -1020,7 +1020,17 @@ void ir_print_metal_visitor::visit(ir_expression *ir)
 			const bool halfCast = (arg_prec == glsl_precision_medium || arg_prec == glsl_precision_low);
 			buffer.asprintf_append (halfCast ? "((half)1.0/(" : "(1.0/(");
 		} else {
-			buffer.asprintf_append ("%s(", operator_glsl_strs[ir->operation]);
+			switch(ir->operation) {
+				case ir_unop_dFdy:
+				case ir_unop_dFdy_coarse:
+				case ir_unop_dFdy_fine:
+					buffer.asprintf_append ("%s(-", operator_glsl_strs[ir->operation]);
+					break;
+
+				default:
+					buffer.asprintf_append ("%s(", operator_glsl_strs[ir->operation]);
+					break;
+			}
 		}
 		if (ir->operands[0])
 			ir->operands[0]->accept(this);