diff --git a/docs/guide/exe_verilator.rst b/docs/guide/exe_verilator.rst
index e4ece604e..727371a69 100644
--- a/docs/guide/exe_verilator.rst
+++ b/docs/guide/exe_verilator.rst
@@ -741,6 +741,8 @@ Summary:
    model has a time resolution that is always compatible with the time
    precision of the upper instantiating module.
 
+   Designs compiled using this option cannot use :vlopt:`--timing` with delays.
+
    See also :vlopt:`--protect-lib`.
 
 .. option:: +libext+<ext>[+<ext>][...]
@@ -1068,6 +1070,8 @@ Summary:
    in the distribution for a demonstration of how to build and use the DPI
    library.
 
+   Designs compiled using this option cannot use :vlopt:`--timing` with delays.
+
 .. option:: --public
 
    This is only for historical debug use.  Using it may result in
diff --git a/docs/guide/verilating.rst b/docs/guide/verilating.rst
index 2af18c1f0..3921a1964 100644
--- a/docs/guide/verilating.rst
+++ b/docs/guide/verilating.rst
@@ -113,6 +113,8 @@ Hierarchy blocks have some limitations including:
   hierarchical model and pass up into another hierarchical model or the top
   module.
 
+* Delays are not allowed in hierarchy blocks.
+
 But, the following usage is supported:
 
 * Nested hierarchy blocks. A hierarchy block may instantiate other
diff --git a/src/Verilator.cpp b/src/Verilator.cpp
index aaf666ea0..9604eb151 100644
--- a/src/Verilator.cpp
+++ b/src/Verilator.cpp
@@ -559,6 +559,9 @@ static void process() {
 
     // Output DPI protected library files
     if (!v3Global.opt.libCreate().empty()) {
+        if (v3Global.rootp()->delaySchedulerp()) {
+            v3warn(E_UNSUPPORTED, "Unsupported: --lib-create with --timing and delays");
+        }
         V3ProtectLib::protect();
         V3EmitV::emitvFiles();
         V3EmitC::emitcFiles();