diff --git a/reference/shaders-msl/asm/frag/undef-variable-store.asm.frag b/reference/shaders-msl/asm/frag/undef-variable-store.asm.frag
index 16658ffc..2cefeb66 100644
--- a/reference/shaders-msl/asm/frag/undef-variable-store.asm.frag
+++ b/reference/shaders-msl/asm/frag/undef-variable-store.asm.frag
@@ -3,8 +3,8 @@
 
 using namespace metal;
 
-constant float4 _38 = float4(0);
-constant float4 _47 = float4(0);
+constant float4 _38 = {};
+constant float4 _47 = {};
 
 struct main0_out
 {
diff --git a/spirv_msl.cpp b/spirv_msl.cpp
index c6be0598..63515fc0 100644
--- a/spirv_msl.cpp
+++ b/spirv_msl.cpp
@@ -1042,7 +1042,7 @@ void CompilerMSL::emit_custom_functions()
 }
 
 // Undefined global memory is not allowed in MSL.
-// Declare constant and init to zeros.
+// Declare constant and init to zeros. Use {}, as global constructors can break Metal.
 void CompilerMSL::declare_undefined_values()
 {
 	bool emitted = false;
@@ -1052,21 +1052,7 @@ void CompilerMSL::declare_undefined_values()
 		{
 			auto &undef = id.get<SPIRUndef>();
 			auto &type = get<SPIRType>(undef.basetype);
-
-			string arg_str;
-			switch (type.basetype)
-			{
-			case SPIRType::Struct:
-				arg_str = "";
-				break;
-
-			default:
-				arg_str = "0";
-				break;
-			}
-			string init_str = type_to_glsl(type) + "(" + arg_str + ")";
-
-			statement("constant ", variable_decl(type, to_name(undef.self), undef.self), " = ", init_str, ";");
+			statement("constant ", variable_decl(type, to_name(undef.self), undef.self), " = {};");
 			emitted = true;
 		}
 	}
@@ -1546,7 +1532,7 @@ void CompilerMSL::emit_instruction(const Instruction &instruction)
 			emit_barrier(ops[0], ops[1], ops[2]);
 		break;
 
-		// OpOuterProduct
+	// OpOuterProduct
 
 	default:
 		CompilerGLSL::emit_instruction(instruction);
@@ -1851,10 +1837,10 @@ void CompilerMSL::emit_glsl_op(uint32_t result_type, uint32_t id, uint32_t eop,
 		break;
 	}
 
-		// TODO:
-		//        GLSLstd450InterpolateAtCentroid (centroid_no_perspective qualifier)
-		//        GLSLstd450InterpolateAtSample (sample_no_perspective qualifier)
-		//        GLSLstd450InterpolateAtOffset
+	// TODO:
+	//        GLSLstd450InterpolateAtCentroid (centroid_no_perspective qualifier)
+	//        GLSLstd450InterpolateAtSample (sample_no_perspective qualifier)
+	//        GLSLstd450InterpolateAtOffset
 
 	default:
 		CompilerGLSL::emit_glsl_op(result_type, id, eop, args, count);
@@ -2739,13 +2725,11 @@ string CompilerMSL::ensure_valid_name(string name, string pfx)
 void CompilerMSL::replace_illegal_names()
 {
 	static const unordered_set<string> keywords = {
-		"kernel",
-		"bias",
+		"kernel", "bias",
 	};
 
 	static const unordered_set<string> illegal_func_names = {
-		"main",
-		"saturate",
+		"main", "saturate",
 	};
 
 	for (auto &id : ids)