diff --git a/elab_lval.cc b/elab_lval.cc
index 659837337..e203c6647 100644
--- a/elab_lval.cc
+++ b/elab_lval.cc
@@ -25,6 +25,7 @@
 # include  "compiler.h"
 # include  <cstdlib>
 # include  <iostream>
+# include  <climits>
 # include  "ivl_assert.h"
 
 /*
@@ -350,7 +351,8 @@ NetAssign_* PEIdent::elaborate_lval_net_word_(Design*des,
       if (NetEConst*word_const = dynamic_cast<NetEConst*>(word)) {
 	    verinum word_val = word_const->value();
 	    long index = word_val.as_long();
-	    if (index < 0 || index >= reg->array_count()) {
+	    assert (reg->array_count() <= LONG_MAX);
+	    if (index < 0 || index >= (long) reg->array_count()) {
 		  cerr << get_fileline() << ": warning: Constant array index "
 		       << (index + reg->array_first())
 		       << " is out of range for array "
diff --git a/vvp/vpi_memory.cc b/vvp/vpi_memory.cc
index 6a58afe99..efcae4e8e 100644
--- a/vvp/vpi_memory.cc
+++ b/vvp/vpi_memory.cc
@@ -225,10 +225,11 @@ static vpiHandle memory_word_put(vpiHandle ref, p_vpi_value val)
 
 	/* Addresses are converted to canonical form by offsetting the
 	   address by the lowest index. */
-      unsigned addr_off = memory_left_range(rfp->mem->mem, 0);
+      long addr_off = memory_left_range(rfp->mem->mem, 0);
       if (memory_right_range(rfp->mem->mem, 0) < addr_off)
 	    addr_off = memory_right_range(rfp->mem->mem, 0);
 
+      assert(addr_off >= 0 && (unsigned) addr_off <= word_addr);
       word_addr -= addr_off;
 
 	/* Build up the word value from whatever format the user