diff --git a/dali/dfu/dfurun.cpp b/dali/dfu/dfurun.cpp
index 74a795261e8..1e7d69f5e53 100644
--- a/dali/dfu/dfurun.cpp
+++ b/dali/dfu/dfurun.cpp
@@ -1427,15 +1427,19 @@ class CDFUengine: public CInterface, implements IDFUengine
                     // keys default wrap for copy
                     if (destination->getWrap()||(iskey&&(cmd==DFUcmd_copy)))
                     {
-                        if (destination->getNumPartsOverride())
-                            throw makeStringExceptionV(-1, "DestinationNumPartOverride is provided but %s", destination->getWrap()?"getWrap is true":"is copying a key");
-                        dst->setNumPartsOverride(srcFile->numParts());
+                        unsigned numOverrideParts = destination->getNumPartsOverride();
+                        if (numOverrideParts)
+                        {
+                            if (srcFile->numParts() != numOverrideParts)
+                                throw makeStringExceptionV(-1, "Destination NumPartsOverride is provided but %s", (iskey&&(cmd==DFUcmd_copy))?"not supported when copying a key":"getWrap is true");
+                        }
+                        dst->setNumParts(srcFile->numParts());
                     }
                     else if (plane)
                     {
                         // use destination defaultSprayParts if requestor doesn't provide num parts
                         if (plane->hasProp("@defaultSprayParts") && destination->getNumPartsOverride()==0)
-                            dst->setNumPartsOverride(plane->getPropInt("@defaultSprayParts"));
+                            dst->setNumParts(plane->getPropInt("@defaultSprayParts"));
                     }
                 }
                 break;
diff --git a/dali/dfu/dfuwu.cpp b/dali/dfu/dfuwu.cpp
index fcd3403e6a6..f90ebbefea2 100644
--- a/dali/dfu/dfuwu.cpp
+++ b/dali/dfu/dfuwu.cpp
@@ -1376,7 +1376,7 @@ class CDFUfileSpec: public CLinkedDFUWUchild, implements IDFUfileSpec
     {
         queryRoot()->setProp("@partmask",val);
     }
-    void setNumParts(unsigned val)
+    virtual void setNumParts(unsigned val) override
     {
         queryRoot()->setPropInt("@numparts",val);
 
diff --git a/dali/dfu/dfuwu.hpp b/dali/dfu/dfuwu.hpp
index 59c15a49e9d..7e56085a5f5 100644
--- a/dali/dfu/dfuwu.hpp
+++ b/dali/dfu/dfuwu.hpp
@@ -279,6 +279,7 @@ interface IDFUfileSpec: extends IConstDFUfileSpec
     virtual void setFromXML(const char *xml) = 0;
     virtual void setCompressed(bool set) = 0;
     virtual void setWrap(bool val) = 0;
+    virtual void setNumParts(unsigned val) = 0;
     virtual void setNumPartsOverride(unsigned num) = 0;
     virtual void setReplicateOffset(int val) = 0;           // sets for all clusters
     virtual void setDiffKey(const char *keyname) = 0;