diff --git a/libraries/bxdf/lama/lama_sss.mtlx b/libraries/bxdf/lama/lama_sss.mtlx
index 1646a09570..ded26871ff 100644
--- a/libraries/bxdf/lama/lama_sss.mtlx
+++ b/libraries/bxdf/lama/lama_sss.mtlx
@@ -45,15 +45,12 @@
   <nodegraph name="IMPL_lama_sss" nodedef="ND_lama_sss">
 
     <!-- DMFP -->
-    <convert name="subsurface_radius_vector" type="vector3">
-      <input name="in" type="color3" interfacename="sssRadius" />
-    </convert>
-    <multiply name="subsurface_radius_scaled" type="vector3">
-      <input name="in1" type="vector3" nodename="subsurface_radius_vector" />
+    <multiply name="subsurface_radius_scaled" type="color3">
+      <input name="in1" type="color3" interfacename="sssRadius" />
       <input name="in2" type="float" interfacename="sssScale" />
     </multiply>
-    <multiply name="subsurface_multiply_unitlength" type="vector3">
-      <input name="in1" type="vector3" nodename="subsurface_radius_scaled" />
+    <multiply name="subsurface_multiply_unitlength" type="color3">
+      <input name="in1" type="color3" nodename="subsurface_radius_scaled" />
       <input name="in2" type="float" interfacename="sssUnitLength" />
     </multiply>
 
@@ -61,7 +58,7 @@
     <subsurface_bsdf name="subsurface_bsdf" type="BSDF">
       <input name="weight" type="float" value="1.0" />
       <input name="color" type="color3" interfacename="color" />
-      <input name="radius" type="vector3" nodename="subsurface_multiply_unitlength" />
+      <input name="radius" type="color3" nodename="subsurface_multiply_unitlength" />
       <input name="anisotropy" type="float" interfacename="sssAnisotropy" />
       <input name="normal" type="vector3" interfacename="normal" />
     </subsurface_bsdf>
diff --git a/libraries/bxdf/open_pbr_surface.mtlx b/libraries/bxdf/open_pbr_surface.mtlx
index 665e369f4b..edd44a5858 100644
--- a/libraries/bxdf/open_pbr_surface.mtlx
+++ b/libraries/bxdf/open_pbr_surface.mtlx
@@ -177,16 +177,13 @@
     </mix>
 
     <!-- Subsurface (non-thin-walled) -->
-    <convert name="subsurface_radius_vector" type="vector3">
-      <input name="in" type="color3" interfacename="subsurface_radius_scale" />
-    </convert>
-    <multiply name="subsurface_radius_scaled" type="vector3">
-      <input name="in1" type="vector3" nodename="subsurface_radius_vector" />
+    <multiply name="subsurface_radius_scaled" type="color3">
+      <input name="in1" type="color3" interfacename="subsurface_radius_scale" />
       <input name="in2" type="float" interfacename="subsurface_radius" />
     </multiply>
     <subsurface_bsdf name="subsurface_bsdf" type="BSDF">
       <input name="color" type="color3" nodename="subsurface_color_nonnegative" />
-      <input name="radius" type="vector3" nodename="subsurface_radius_scaled" />
+      <input name="radius" type="color3" nodename="subsurface_radius_scaled" />
       <input name="anisotropy" type="float" interfacename="subsurface_scatter_anisotropy" />
       <input name="normal" type="vector3" interfacename="geometry_normal" />
     </subsurface_bsdf>
diff --git a/libraries/bxdf/standard_surface.mtlx b/libraries/bxdf/standard_surface.mtlx
index fe87f260b0..20ef806699 100644
--- a/libraries/bxdf/standard_surface.mtlx
+++ b/libraries/bxdf/standard_surface.mtlx
@@ -230,17 +230,14 @@
       <input name="color" type="color3" nodename="coat_affected_subsurface_color" />
       <input name="normal" type="vector3" interfacename="normal" />
     </translucent_bsdf>
-    <convert name="subsurface_radius_vector" type="vector3">
-      <input name="in" type="color3" interfacename="subsurface_radius" />
-    </convert>
-    <multiply name="subsurface_radius_scaled" type="vector3">
-      <input name="in1" type="vector3" nodename="subsurface_radius_vector" />
+    <multiply name="subsurface_radius_scaled" type="color3">
+      <input name="in1" type="color3" interfacename="subsurface_radius" />
       <input name="in2" type="float" interfacename="subsurface_scale" />
     </multiply>
     <subsurface_bsdf name="subsurface_bsdf" type="BSDF">
       <input name="weight" type="float" value="1.0" />
       <input name="color" type="color3" nodename="coat_affected_subsurface_color" />
-      <input name="radius" type="vector3" nodename="subsurface_radius_scaled" />
+      <input name="radius" type="color3" nodename="subsurface_radius_scaled" />
       <input name="anisotropy" type="float" interfacename="subsurface_anisotropy" />
       <input name="normal" type="vector3" interfacename="normal" />
     </subsurface_bsdf>
diff --git a/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
index 17a4aff2cb..da0e3cc12a 100644
--- a/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
+++ b/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
@@ -1,4 +1,4 @@
-void mx_subsurface_bsdf(float weight, color _color, vector radius, float anisotropy, normal N, output BSDF bsdf)
+void mx_subsurface_bsdf(float weight, color _color, color radius, float anisotropy, normal N, output BSDF bsdf)
 {
     // TODO: Subsurface closure is not supported by vanilla OSL.
     bsdf.response = _color * weight * diffuse(N);
diff --git a/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl b/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl
index 826eee2bd6..d3e520b137 100644
--- a/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl
+++ b/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl
@@ -1,4 +1,4 @@
-void mx_subsurface_bsdf(float weight, color _color, vector radius, float anisotropy, normal N, output BSDF bsdf)
+void mx_subsurface_bsdf(float weight, color _color, color radius, float anisotropy, normal N, output BSDF bsdf)
 {
     // TODO: Subsurface closure is not supported by vanilla OSL.
     bsdf = _color * weight * diffuse(N);
diff --git a/libraries/pbrlib/pbrlib_defs.mtlx b/libraries/pbrlib/pbrlib_defs.mtlx
index a64144b66f..2e71f80611 100644
--- a/libraries/pbrlib/pbrlib_defs.mtlx
+++ b/libraries/pbrlib/pbrlib_defs.mtlx
@@ -117,7 +117,7 @@
   <nodedef name="ND_subsurface_bsdf" node="subsurface_bsdf" bsdf="R" nodegroup="pbr" doc="A subsurface scattering BSDF for true subsurface scattering.">
     <input name="weight" type="float" value="1.0" uimin="0.0" uimax="1.0" />
     <input name="color" type="color3" value="0.18, 0.18, 0.18" />
-    <input name="radius" type="vector3" value="1.0, 1.0, 1.0" />
+    <input name="radius" type="color3" value="1.0, 1.0, 1.0" />
     <input name="anisotropy" type="float" value="0.0" />
     <input name="normal" type="vector3" defaultgeomprop="Nworld" />
     <output name="out" type="BSDF" />
diff --git a/resources/Materials/TestSuite/pbrlib/surfaceshader/surface_ops.mtlx b/resources/Materials/TestSuite/pbrlib/surfaceshader/surface_ops.mtlx
index 8974d4f8d4..825491a45b 100644
--- a/resources/Materials/TestSuite/pbrlib/surfaceshader/surface_ops.mtlx
+++ b/resources/Materials/TestSuite/pbrlib/surfaceshader/surface_ops.mtlx
@@ -7,7 +7,7 @@
     <subsurface_bsdf name="subsurface_brdf1" type="BSDF">
       <input name="weight" type="float" value="1.0" />
       <input name="color" type="color3" value="0.18, 0.18, 0.18" />
-      <input name="radius" type="vector3" value="1.0, 1.0, 1.0" />
+      <input name="radius" type="color3" value="1.0, 1.0, 1.0" />
       <input name="anisotropy" type="float" value="0.0" />
       <input name="normal" type="vector3" value="0.0, 0.0, 0.0" />
     </subsurface_bsdf>
diff --git a/source/MaterialXCore/Version.cpp b/source/MaterialXCore/Version.cpp
index 5fd7829d56..9c0022bd6a 100644
--- a/source/MaterialXCore/Version.cpp
+++ b/source/MaterialXCore/Version.cpp
@@ -1130,6 +1130,18 @@ void Document::upgradeVersion()
                     unusedNodes.push_back(top);
                 }
             }
+            else if (nodeCategory == "subsurface_bsdf")
+            {
+                InputPtr radiusInput = node->getInput("radius");
+                if (radiusInput && radiusInput->getType() == "vector3")
+                {
+                    GraphElementPtr graph = node->getAncestorOfType<GraphElement>();
+                    NodePtr convertNode = graph->addNode("convert", graph->createValidChildName("convert"), "color3");
+                    copyInputWithBindings(node, "radius", convertNode, "in");
+                    radiusInput->setConnectedNode(convertNode);
+                    radiusInput->setType("color3");
+                }
+            }
             else if (nodeCategory == "switch")
             {
                 // Upgrade switch nodes from 5 to 10 inputs, handling the fallback behavior for
diff --git a/source/MaterialXGenMdl/mdl/materialx/pbrlib_1_6.mdl b/source/MaterialXGenMdl/mdl/materialx/pbrlib_1_6.mdl
index 5e2e74e733..ef2e090a49 100644
--- a/source/MaterialXGenMdl/mdl/materialx/pbrlib_1_6.mdl
+++ b/source/MaterialXGenMdl/mdl/materialx/pbrlib_1_6.mdl
@@ -333,7 +333,7 @@ export material mx_generalized_schlick_bsdf(
 export material mx_subsurface_bsdf(
     float  mxp_weight    = 1.0 [[ anno::unused() ]],
     color  mxp_color     = color(0.18),
-    float3 mxp_radius    = float3(1.0), // TODO: should probably be a color in MTLX Spec
+    color  mxp_radius    = color(1.0),
     float  mxp_anisotropy = 0.0,
     float3 mxp_normal    = state::normal() [[ anno::unused() ]]
 ) [[ 
@@ -357,7 +357,7 @@ export material mx_subsurface_bsdf(
     color alpha = 
         (white - albedo_sq) / (white - mxp_anisotropy * albedo_sq);
 
-    color radius_inv = white/color(mxp_radius);
+    color radius_inv = white / mxp_radius;
 
     color sigma_s = alpha * radius_inv;
     color sigma_a = radius_inv - sigma_s;