10 files changed, 10 insertions, 10 deletions
diff --git a/src/Array.cpp b/src/Array.cpp
index 22c254b..8838e5b 100644
--- a/src/Array.cpp
+++ b/src/Array.cpp
@@ -58,7 +58,7 @@ Array::Array(const PList::Array& a)
     array_fill(this, _array, _node);
 }
 
-Array& Array::operator=(PList::Array& a)
+Array& Array::operator=(const PList::Array& a)
 {
     plist_free(_node);
     for (unsigned int it = 0; it < _array.size(); it++)
diff --git a/src/Boolean.cpp b/src/Boolean.cpp
index 9f14904..2c871c8 100644
--- a/src/Boolean.cpp
+++ b/src/Boolean.cpp
@@ -37,7 +37,7 @@ Boolean::Boolean(const PList::Boolean& b) : Node(PLIST_BOOLEAN)
     plist_set_bool_val(_node, b.GetValue());
 }
 
-Boolean& Boolean::operator=(PList::Boolean& b)
+Boolean& Boolean::operator=(const PList::Boolean& b)
 {
     plist_free(_node);
     _node = plist_copy(b.GetPlist());
diff --git a/src/Data.cpp b/src/Data.cpp
index 89b4f4e..4515388 100644
--- a/src/Data.cpp
+++ b/src/Data.cpp
@@ -38,7 +38,7 @@ Data::Data(const PList::Data& d) : Node(PLIST_DATA)
     plist_set_data_val(_node, &b[0], b.size());
 }
 
-Data& Data::operator=(PList::Data& b)
+Data& Data::operator=(const PList::Data& b)
 {
     plist_free(_node);
     _node = plist_copy(b.GetPlist());
diff --git a/src/Date.cpp b/src/Date.cpp
index a3c8592..8b8e650 100644
--- a/src/Date.cpp
+++ b/src/Date.cpp
@@ -38,7 +38,7 @@ Date::Date(const PList::Date& d) : Node(PLIST_DATE)
     plist_set_date_val(_node, t.tv_sec, t.tv_usec);
 }
 
-Date& Date::operator=(PList::Date& d)
+Date& Date::operator=(const PList::Date& d)
 {
     plist_free(_node);
     _node = plist_copy(d.GetPlist());
diff --git a/src/Dictionary.cpp b/src/Dictionary.cpp
index 6da0eee..20e9710 100644
--- a/src/Dictionary.cpp
+++ b/src/Dictionary.cpp
@@ -62,7 +62,7 @@ Dictionary::Dictionary(const PList::Dictionary& d)
     dictionary_fill(this, _map, _node);
 }
 
-Dictionary& Dictionary::operator=(PList::Dictionary& d)
+Dictionary& Dictionary::operator=(const PList::Dictionary& d)
 {
     for (Dictionary::iterator it = _map.begin(); it != _map.end(); it++)
     {
diff --git a/src/Integer.cpp b/src/Integer.cpp
index d394ee1..a40d026 100644
--- a/src/Integer.cpp
+++ b/src/Integer.cpp
@@ -37,7 +37,7 @@ Integer::Integer(const PList::Integer& i) : Node(PLIST_UINT)
     plist_set_uint_val(_node, i.GetValue());
 }
 
-Integer& Integer::operator=(PList::Integer& i)
+Integer& Integer::operator=(const PList::Integer& i)
 {
     plist_free(_node);
     _node = plist_copy(i.GetPlist());
diff --git a/src/Key.cpp b/src/Key.cpp
index 8c96e59..8ba497a 100644
--- a/src/Key.cpp
+++ b/src/Key.cpp
@@ -37,7 +37,7 @@ Key::Key(const PList::Key& k) : Node(PLIST_UINT)
     plist_set_key_val(_node, k.GetValue().c_str());
 }
 
-Key& Key::operator=(PList::Key& k)
+Key& Key::operator=(const PList::Key& k)
 {
     plist_free(_node);
     _node = plist_copy(k.GetPlist());
diff --git a/src/Real.cpp b/src/Real.cpp
index 3ac67f2..6bdb920 100644
--- a/src/Real.cpp
+++ b/src/Real.cpp
@@ -37,7 +37,7 @@ Real::Real(const PList::Real& d) : Node(PLIST_UINT)
     plist_set_real_val(_node, d.GetValue());
 }
 
-Real& Real::operator=(PList::Real& d)
+Real& Real::operator=(const PList::Real& d)
 {
     plist_free(_node);
     _node = plist_copy(d.GetPlist());
diff --git a/src/String.cpp b/src/String.cpp
index 39717c2..cd4f98f 100644
--- a/src/String.cpp
+++ b/src/String.cpp
@@ -37,7 +37,7 @@ String::String(const PList::String& s) : Node(PLIST_UINT)
     plist_set_string_val(_node, s.GetValue().c_str());
 }
 
-String& String::operator=(PList::String& s)
+String& String::operator=(const PList::String& s)
 {
     plist_free(_node);
     _node = plist_copy(s.GetPlist());
diff --git a/src/Uid.cpp b/src/Uid.cpp
index 204cd68..e83ed27 100644
--- a/src/Uid.cpp
+++ b/src/Uid.cpp
@@ -37,7 +37,7 @@ Uid::Uid(const PList::Uid& i) : Node(PLIST_UID)
     plist_set_uid_val(_node, i.GetValue());
 }
 
-Uid& Uid::operator=(PList::Uid& i)
+Uid& Uid::operator=(const PList::Uid& i)
 {
     plist_free(_node);
     _node = plist_copy(i.GetPlist());