diff --git a/intern/cycles/blender/python.cpp b/intern/cycles/blender/python.cpp
index 9e42f6b8b60..1e9478ea32d 100644
--- a/intern/cycles/blender/python.cpp
+++ b/intern/cycles/blender/python.cpp
@@ -478,6 +478,7 @@ static PyObject *osl_update_node_func(PyObject * /*self*/, PyObject *args)
 
     /* Read metadata. */
     bool is_bool_param = false;
+    bool hide_value = !param->validdefault;
     ustring param_label = param->name;
 
     for (const OSL::OSLQuery::Parameter &metadata : param->metadata) {
@@ -487,6 +488,9 @@ static PyObject *osl_update_node_func(PyObject * /*self*/, PyObject *args)
           if (metadata.sdefault[0] == "boolean" || metadata.sdefault[0] == "checkBox") {
             is_bool_param = true;
           }
+          else if (metadata.sdefault[0] == "null") {
+            hide_value = true;
+          }
         }
         else if (metadata.name == "label") {
           /* Socket label. */
@@ -596,6 +600,9 @@ static PyObject *osl_update_node_func(PyObject * /*self*/, PyObject *args)
             if (b_sock.name() != param_label) {
               b_sock.name(param_label.string());
             }
+            if (b_sock.hide_value() != hide_value) {
+              b_sock.hide_value(hide_value);
+            }
             used_sockets.insert(b_sock.ptr.data);
             found_existing = true;
           }
@@ -635,6 +642,8 @@ static PyObject *osl_update_node_func(PyObject * /*self*/, PyObject *args)
         set_boolean(b_sock.ptr, "default_value", default_boolean);
       }
 
+      b_sock.hide_value(hide_value);
+
       used_sockets.insert(b_sock.ptr.data);
     }
   }
diff --git a/intern/cycles/graph/node_type.h b/intern/cycles/graph/node_type.h
index 9101b51bb9f..7725396e4f1 100644
--- a/intern/cycles/graph/node_type.h
+++ b/intern/cycles/graph/node_type.h
@@ -66,7 +66,9 @@ struct SocketType {
     LINK_NORMAL = (1 << 8),
     LINK_POSITION = (1 << 9),
     LINK_TANGENT = (1 << 10),
-    DEFAULT_LINK_MASK = (1 << 4) | (1 << 5) | (1 << 6) | (1 << 7) | (1 << 8) | (1 << 9) | (1 << 10)
+    LINK_OSL_INITIALIZER = (1 << 11),
+    DEFAULT_LINK_MASK = (1 << 4) | (1 << 5) | (1 << 6) | (1 << 7) | (1 << 8) | (1 << 9) |
+                        (1 << 10) | (1 << 11)
   };
 
   ustring name;
diff --git a/intern/cycles/scene/osl.cpp b/intern/cycles/scene/osl.cpp
index 93839facdbe..2ff36ff7fca 100644
--- a/intern/cycles/scene/osl.cpp
+++ b/intern/cycles/scene/osl.cpp
@@ -525,6 +525,7 @@ OSLNode *OSLShaderManager::osl_node(ShaderGraph *graph,
 
     SocketType::Type socket_type;
 
+    /* Read type and default value. */
     if (param->isclosure) {
       socket_type = SocketType::CLOSURE;
     }
@@ -579,7 +580,21 @@ OSLNode *OSLShaderManager::osl_node(ShaderGraph *graph,
       node->add_output(param->name, socket_type);
     }
     else {
-      node->add_input(param->name, socket_type);
+      /* Detect if we should leave parameter initialization to OSL, either though
+       * not constant default or widget metadata. */
+      int socket_flags = 0;
+      if (!param->validdefault) {
+        socket_flags |= SocketType::LINK_OSL_INITIALIZER;
+      }
+      for (const OSL::OSLQuery::Parameter &metadata : param->metadata) {
+        if (metadata.type == TypeDesc::STRING) {
+          if (metadata.name == "widget" && metadata.sdefault[0] == "null") {
+            socket_flags |= SocketType::LINK_OSL_INITIALIZER;
+          }
+        }
+      }
+
+      node->add_input(param->name, socket_type, socket_flags);
     }
   }
 
@@ -702,8 +717,12 @@ void OSLCompiler::add(ShaderNode *node, const char *name, bool isfilepath)
   foreach (ShaderInput *input, node->inputs) {
     if (!input->link) {
       /* checks to untangle graphs */
-      if (node_skip_input(node, input))
+      if (node_skip_input(node, input)) {
         continue;
+      }
+      if (input->flags() & SocketType::LINK_OSL_INITIALIZER) {
+        continue;
+      }
 
       string param_name = compatible_name(node, input);
       const SocketType &socket = input->socket_type;
diff --git a/intern/cycles/scene/shader_nodes.cpp b/intern/cycles/scene/shader_nodes.cpp
index 2c1cd3ee737..c1189e3795c 100644
--- a/intern/cycles/scene/shader_nodes.cpp
+++ b/intern/cycles/scene/shader_nodes.cpp
@@ -7257,12 +7257,12 @@ char *OSLNode::input_default_value()
   return (char *)this + align_up(sizeof(OSLNode), 16) + inputs_size;
 }
 
-void OSLNode::add_input(ustring name, SocketType::Type socket_type)
+void OSLNode::add_input(ustring name, SocketType::Type socket_type, const int flags)
 {
   char *memory = input_default_value();
   size_t offset = memory - (char *)this;
   const_cast<NodeType *>(type)->register_input(
-      name, name, socket_type, offset, memory, NULL, NULL, SocketType::LINKABLE);
+      name, name, socket_type, offset, memory, NULL, NULL, flags | SocketType::LINKABLE);
 }
 
 void OSLNode::add_output(ustring name, SocketType::Type socket_type)
diff --git a/intern/cycles/scene/shader_nodes.h b/intern/cycles/scene/shader_nodes.h
index 3ab7b1041b5..0a5dd99e8bf 100644
--- a/intern/cycles/scene/shader_nodes.h
+++ b/intern/cycles/scene/shader_nodes.h
@@ -1525,7 +1525,7 @@ class OSLNode final : public ShaderNode {
   ShaderNode *clone(ShaderGraph *graph) const;
 
   char *input_default_value();
-  void add_input(ustring name, SocketType::Type type);
+  void add_input(ustring name, SocketType::Type type, const int flags = 0);
   void add_output(ustring name, SocketType::Type type);
 
   SHADER_NODE_NO_CLONE_CLASS(OSLNode)