diff --git a/src/factory/Compare.cpp b/src/factory/Compare.cpp
index 6d902df..06b4e27 100644
--- a/src/factory/Compare.cpp
+++ b/src/factory/Compare.cpp
@@ -251,7 +251,13 @@ bool compareField(const PVStructureArray* left, const PVStructureArray* right)
         lit!=lend;
         ++lit, ++rit)
     {
-        if(**lit != **rit)
+        // element can be null
+        if (!(*lit) || !(*rit))
+        {
+            if (*lit || *rit)
+                return false;
+        }
+        else if (**lit != **rit)
             return false;
     }
     return true;
@@ -304,7 +310,13 @@ bool compareField(const PVUnionArray* left, const PVUnionArray* right)
         lit!=lend;
         ++lit, ++rit)
     {
-        if(**lit != **rit)
+        // element can be null
+        if (!(*lit) || !(*rit))
+        {
+            if (*lit || *rit)
+                return false;
+        }
+        else if (**lit != **rit)
             return false;
     }
     return true;
diff --git a/src/factory/PVStructureArray.cpp b/src/factory/PVStructureArray.cpp
index 29e4663..b54ff85 100644
--- a/src/factory/PVStructureArray.cpp
+++ b/src/factory/PVStructureArray.cpp
@@ -232,8 +232,13 @@ std::ostream& PVStructureArray::dumpValue(std::ostream& o) const
 std::ostream& PVStructureArray::dumpValue(std::ostream& o, std::size_t index) const
 {
     const_svector temp(view());
-    if(index<temp.size())
-        o << *temp[index];
+    if (index<temp.size())
+    {
+        if (temp[index])
+            o << *temp[index];
+        else
+            o << "(none)" << std::endl;
+    }
     return o;
 }
 
diff --git a/src/factory/PVUnionArray.cpp b/src/factory/PVUnionArray.cpp
index dc556cf..ccce916 100644
--- a/src/factory/PVUnionArray.cpp
+++ b/src/factory/PVUnionArray.cpp
@@ -231,8 +231,13 @@ std::ostream& PVUnionArray::dumpValue(std::ostream& o) const
 std::ostream& PVUnionArray::dumpValue(std::ostream& o, std::size_t index) const
 {
     const_svector temp(view());
-    if(index<temp.size())
-        o << *temp[index];
+    if (index<temp.size())
+    {
+        if (temp[index])
+            o << *temp[index];
+        else
+            o << "(none)" << std::endl;
+    }
     return o;
 }