diff --git a/src/testshade/simplerend.cpp b/src/testshade/simplerend.cpp
index e6d63688d..0fdcc71da 100644
--- a/src/testshade/simplerend.cpp
+++ b/src/testshade/simplerend.cpp
@@ -695,8 +695,21 @@ SimpleRenderer::build_interpolated_getter(const ShaderGroup& group,
 
     static const OIIO::ustring rs_get_attribute_constant_int(
         "rs_get_attribute_constant_int");
+    static const OIIO::ustring rs_get_attribute_constant_int2(
+        "rs_get_attribute_constant_int2");
+    static const OIIO::ustring rs_get_attribute_constant_int3(
+        "rs_get_attribute_constant_int3");
+    static const OIIO::ustring rs_get_attribute_constant_int4(
+        "rs_get_attribute_constant_int4");
+
     static const OIIO::ustring rs_get_attribute_constant_float(
         "rs_get_attribute_constant_float");
+    static const OIIO::ustring rs_get_attribute_constant_float2(
+        "rs_get_attribute_constant_float2");
+    static const OIIO::ustring rs_get_attribute_constant_float3(
+        "rs_get_attribute_constant_float3");
+    static const OIIO::ustring rs_get_attribute_constant_float4(
+        "rs_get_attribute_constant_float4");
 
     if (param_name == RS::Hashes::s && type == OIIO::TypeDesc::TypeFloat) {
         spec.set(rs_get_interpolated_s,
@@ -727,14 +740,49 @@ SimpleRenderer::build_interpolated_getter(const ShaderGroup& group,
         spec.set(rs_get_interpolated_test);
     } else if (const OIIO::ParamValue* p = userdata.find_pv(param_name, type)) {
         if (p->type().basetype == OIIO::TypeDesc::INT) {
-            spec.set(rs_get_attribute_constant_int,
-                     ((int*)p->data())[0]);
-            return;
+            if (p->type().aggregate == 1) {
+                spec.set(rs_get_attribute_constant_int,
+                            ((int*)p->data())[0]);
+                return;
+            } else if (p->type().aggregate == 2) {
+                spec.set(rs_get_attribute_constant_int2,
+                            ((int*)p->data())[0], ((int*)p->data())[1]);
+                return;
+            } else if (p->type().aggregate == 3) {
+                spec.set(rs_get_attribute_constant_int3,
+                            ((int*)p->data())[0], ((int*)p->data())[1],
+                            ((int*)p->data())[2]);
+                return;
+            } else if (p->type().aggregate == 4) {
+                spec.set(rs_get_attribute_constant_int4,
+                            ((int*)p->data())[0], ((int*)p->data())[1],
+                            ((int*)p->data())[2], ((int*)p->data())[3]);
+                return;
+            }
         } else if (p->type().basetype == OIIO::TypeDesc::FLOAT) {
-            spec.set(rs_get_attribute_constant_float,
-                     ((float*)p->data())[0],
-                     InterpolatedSpecBuiltinArg::Derivatives);
-            return;
+            if (p->type().aggregate == 1) {
+                spec.set(rs_get_attribute_constant_float,
+                            ((float*)p->data())[0],
+                            InterpolatedSpecBuiltinArg::Derivatives);
+                return;
+            } else if (p->type().aggregate == 2) {
+                spec.set(rs_get_attribute_constant_float2,
+                            ((float*)p->data())[0], ((float*)p->data())[1],
+                            InterpolatedSpecBuiltinArg::Derivatives);
+                return;
+            } else if (p->type().aggregate == 3) {
+                spec.set(rs_get_attribute_constant_float3,
+                            ((float*)p->data())[0], ((float*)p->data())[1],
+                            ((float*)p->data())[2],
+                            InterpolatedSpecBuiltinArg::Derivatives);
+                return;
+            } else if (p->type().aggregate == 4) {
+                spec.set(rs_get_attribute_constant_float4,
+                            ((float*)p->data())[0], ((float*)p->data())[1],
+                            ((float*)p->data())[2], ((float*)p->data())[3],
+                            InterpolatedSpecBuiltinArg::Derivatives);
+                return;
+            }
         }
     }
 }