diff --git a/src/graphic/Fast3D/gfx_metal_shader.cpp b/src/graphic/Fast3D/gfx_metal_shader.cpp
index af841f858..cd6ae2c09 100644
--- a/src/graphic/Fast3D/gfx_metal_shader.cpp
+++ b/src/graphic/Fast3D/gfx_metal_shader.cpp
@@ -254,11 +254,22 @@ MTL::VertexDescriptor* gfx_metal_build_shader(char buf[8192], size_t& num_floats
     append_line(buf, &len, "}");
     // end vertex shader
 
+    append_line(buf, &len, "float mod(float a, float b) {");
+    append_line(buf, &len, "    return float(a - b * floor(a / b));");
+    append_line(buf, &len, "}");
+
     append_line(buf, &len, "float3 mod(float3 a, float3 b) {");
     append_line(
         buf, &len,
         "    return float3(a.x - b.x * floor(a.x / b.x), a.y - b.y * floor(a.y / b.y), a.z - b.z * floor(a.z / b.z));");
     append_line(buf, &len, "}");
+
+    append_line(buf, &len, "float4 mod(float4 a, float4 b) {");
+    append_line(buf, &len,
+                "    return float4(a.x - b.x * floor(a.x / b.x), a.y - b.y * floor(a.y / b.y), a.z - b.z * floor(a.z / "
+                "b.z), a.w - b.w * floor(a.w / b.w));");
+    append_line(buf, &len, "}");
+
     append_line(buf, &len, "#define WRAP(x, low, high) mod((x)-(low), (high)-(low)) + (low)");
 
     // fragment shader