diff --git a/src/Type.h b/src/Type.h
index 63e65bd7f771..af5447350810 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -304,6 +304,10 @@ struct Type {
      * lanes: The number of vector elements in the type. */
     Type(halide_type_code_t code, int bits, int lanes, const halide_handle_cplusplus_type *handle_type = nullptr)
         : type(code, (uint8_t)bits, (uint16_t)lanes), handle_type(handle_type) {
+        user_assert(lanes == type.lanes)
+            << "Halide only supports vector types with up to 65535 lanes. " << lanes << " lanes requested.";
+        user_assert(bits == type.bits)
+            << "Halide only supports types with up to 255 bits. " << bits << " bits requested.";
     }
 
     /** Trivial copy constructor. */
diff --git a/test/correctness/vector_reductions.cpp b/test/correctness/vector_reductions.cpp
index b7b4e85354ce..f1c250cfec3d 100644
--- a/test/correctness/vector_reductions.cpp
+++ b/test/correctness/vector_reductions.cpp
@@ -19,7 +19,11 @@ void add_tasks(const Target &target, std::vector<Task> &tasks) {
             const int src_lanes = dst_lanes * reduce_factor;
             for (Type src_type : types) {
                 for (int widen_factor : {1, 2, 4}) {
-                    Type dst_type = src_type.with_bits(src_type.bits() * widen_factor);
+                    int dst_bits = src_type.bits() * widen_factor;
+                    if (dst_bits > 64) {
+                        continue;
+                    }
+                    Type dst_type = src_type.with_bits(dst_bits);
                     if (std::find(types.begin(), types.end(), dst_type) == types.end()) {
                         continue;
                     }