diff --git a/hw/xbox/nv2a/pgraph/glsl/vsh-ff.c b/hw/xbox/nv2a/pgraph/glsl/vsh-ff.c
index 8fcf0626aa..2412826647 100644
--- a/hw/xbox/nv2a/pgraph/glsl/vsh-ff.c
+++ b/hw/xbox/nv2a/pgraph/glsl/vsh-ff.c
@@ -422,7 +422,7 @@ GLSL_DEFINE(materialEmissionColor, GLSL_LTCTXA(NV_IGRAPH_XF_LTCTXA_CM_COL) ".xyz
 
     mstring_append(body,
     "   oPos = tPosition * compositeMat;\n"
-    "   oPos.w = (2.0f * step(0.0f, oPos.w) - 1.0f) * clamp(abs(oPos.w), 5.421011e-20, 1.8446744e19);\n"
+    "   oPos.w = clampAwayZeroInf(oPos.w);\n"
     "   oPos = invViewport * oPos;\n"
     );
 
diff --git a/hw/xbox/nv2a/pgraph/glsl/vsh-prog.c b/hw/xbox/nv2a/pgraph/glsl/vsh-prog.c
index 66fd4df9d0..0530e7ea7b 100644
--- a/hw/xbox/nv2a/pgraph/glsl/vsh-prog.c
+++ b/hw/xbox/nv2a/pgraph/glsl/vsh-prog.c
@@ -735,8 +735,8 @@ static const char* vsh_header =
     "#define RCC(dest, mask, src) dest.mask = _RCC(_in(src).x).mask\n"
     "vec4 _RCC(float src)\n"
     "{\n"
-    "  src = (2.0f * step(0.0f, src) - 1.0f) * clamp(abs(src), 5.421011e-20, 1.8446744e19);\n"
-    "  return vec4(1.0 / src);\n"
+    "  float t = clampAwayZeroInf(1.0 / src);\n"
+    "  return vec4(t);\n"
     "}\n"
     "\n"
     "#define RSQ(dest, mask, src) dest.mask = _RSQ(_in(src).x).mask\n"
@@ -838,7 +838,7 @@ void pgraph_gen_vsh_prog_glsl(uint16_t version,
 
     mstring_append(body,
         "  oPos.z = oPos.z / clipRange.y;\n"
-        "  oPos.w = (2.0f * step(0.0f, oPos.w) - 1.0f) * clamp(abs(oPos.w), 5.421011e-20, 1.8446744e19);\n"
+        "  oPos.w = clampAwayZeroInf(oPos.w);\n"
 
         /* Undo perspective divide by w.
          * Note that games may also have vertex shaders that do
diff --git a/hw/xbox/nv2a/pgraph/glsl/vsh.c b/hw/xbox/nv2a/pgraph/glsl/vsh.c
index 2a49c1f11a..e03f95eb27 100644
--- a/hw/xbox/nv2a/pgraph/glsl/vsh.c
+++ b/hw/xbox/nv2a/pgraph/glsl/vsh.c
@@ -72,6 +72,15 @@ MString *pgraph_gen_vsh_glsl(const ShaderState *state, bool prefix_outputs)
         "    float y = float(bitfieldExtract(cmp, 11, 11)) / 1023.0;\n"
         "    float z = float(bitfieldExtract(cmp, 22, 10)) / 511.0;\n"
         "    return vec4(x, y, z, 1);\n"
+        "}\n"
+        "\n"
+        "float clampAwayZeroInf(float t) {\n"
+        "  if (t > 0.0 || floatBitsToUint(t) == 0) {\n"
+        "    t = clamp(t, 5.421011e-20, 1.8446744e19);\n"
+        "  } else {\n"
+        "    t = clamp(t, -1.8446744e19, -5.421011e-20);\n"
+        "  }\n"
+        "  return t;\n"
         "}\n");
 
     pgraph_get_glsl_vtx_header(header, state->vulkan, state->smooth_shading,