diff --git a/src/d3d9/d3d9_device.cpp b/src/d3d9/d3d9_device.cpp
index 3e5cd6ee6..536c6331a 100644
--- a/src/d3d9/d3d9_device.cpp
+++ b/src/d3d9/d3d9_device.cpp
@@ -5636,7 +5636,8 @@ namespace dxvk {
     viewport = VkViewport{
       float(vp.X)     + cf,    float(vp.Height + vp.Y) + cf,
       float(vp.Width),        -float(vp.Height),
-      vp.MinZ,                 std::max(vp.MaxZ, vp.MinZ + zBias),
+      std::clamp(vp.MinZ,                            0.0f, 1.0f),
+      std::clamp(std::max(vp.MaxZ, vp.MinZ + zBias), 0.0f, 1.0f),
     };
 
     // Scissor rectangles. Vulkan does not provide an easy way