diff --git a/opm/parser/eclipse/Deck/Deck.cpp b/opm/parser/eclipse/Deck/Deck.cpp
index 9c6356b5c..7ef370b5c 100644
--- a/opm/parser/eclipse/Deck/Deck.cpp
+++ b/opm/parser/eclipse/Deck/Deck.cpp
@@ -32,19 +32,19 @@ namespace Opm {
         return m_keywords->hasKeyword(keyword);
     }
 
-    void Deck::addKeyword( DeckKeywordPtr keyword) {
+    void Deck::addKeyword( DeckKeywordConstPtr keyword) {
         m_keywords->addKeyword(keyword);
     }
 
-    DeckKeywordPtr Deck::getKeyword(const std::string& keyword, size_t index) const {
+    DeckKeywordConstPtr Deck::getKeyword(const std::string& keyword, size_t index) const {
         return m_keywords->getKeyword(keyword , index);
     }
 
-    DeckKeywordPtr Deck::getKeyword(const std::string& keyword) const {
+    DeckKeywordConstPtr Deck::getKeyword(const std::string& keyword) const {
         return m_keywords->getKeyword(keyword);
     }
 
-    DeckKeywordPtr Deck::getKeyword(size_t index) const {
+    DeckKeywordConstPtr Deck::getKeyword(size_t index) const {
         return m_keywords->getKeyword(index);
     }
 
@@ -52,7 +52,7 @@ namespace Opm {
         return m_keywords->numKeywords( keyword );
     }
 
-    const std::vector<DeckKeywordPtr>& Deck::getKeywordList(const std::string& keyword) const {
+    const std::vector<DeckKeywordConstPtr>& Deck::getKeywordList(const std::string& keyword) const {
         return m_keywords->getKeywordList( keyword );
     }
 
diff --git a/opm/parser/eclipse/Deck/Deck.hpp b/opm/parser/eclipse/Deck/Deck.hpp
index c3df47473..04dbab68e 100644
--- a/opm/parser/eclipse/Deck/Deck.hpp
+++ b/opm/parser/eclipse/Deck/Deck.hpp
@@ -32,13 +32,13 @@ namespace Opm {
     public:
         Deck();
         bool hasKeyword( const std::string& keyword ) const;
-        void addKeyword( DeckKeywordPtr keyword);
-        DeckKeywordPtr getKeyword(const std::string& keyword , size_t index) const;
-        DeckKeywordPtr getKeyword(const std::string& keyword) const;
-        DeckKeywordPtr getKeyword(size_t index) const;
+        void addKeyword( DeckKeywordConstPtr keyword);
+        DeckKeywordConstPtr getKeyword(const std::string& keyword , size_t index) const;
+        DeckKeywordConstPtr getKeyword(const std::string& keyword) const;
+        DeckKeywordConstPtr getKeyword(size_t index) const;
 
         size_t numKeywords(const std::string& keyword) const;
-        const std::vector<DeckKeywordPtr>& getKeywordList(const std::string& keyword) const;
+        const std::vector<DeckKeywordConstPtr>& getKeywordList(const std::string& keyword) const;
         size_t size() const;
         void initUnitSystem();
         std::shared_ptr<UnitSystem> getDefaultUnitSystem() const;
diff --git a/opm/parser/eclipse/Deck/KeywordContainer.cpp b/opm/parser/eclipse/Deck/KeywordContainer.cpp
index 3c4c08f2c..b80b4df8b 100644
--- a/opm/parser/eclipse/Deck/KeywordContainer.cpp
+++ b/opm/parser/eclipse/Deck/KeywordContainer.cpp
@@ -36,30 +36,30 @@ namespace Opm {
         return m_keywordList.size();
     }
 
-    void KeywordContainer::addKeyword(DeckKeywordPtr keyword) {
+    void KeywordContainer::addKeyword(DeckKeywordConstPtr keyword) {
         m_keywordList.push_back(keyword);
 
         if (!hasKeyword(keyword->name())) {
-            m_keywordMap[keyword->name()] = std::vector<DeckKeywordPtr>();
+            m_keywordMap[keyword->name()] = std::vector<DeckKeywordConstPtr>();
         }
 
         {
-            std::vector<DeckKeywordPtr>& keywordList = m_keywordMap[keyword->name()];
+            std::vector<DeckKeywordConstPtr>& keywordList = m_keywordMap[keyword->name()];
             keywordList.push_back(keyword);
         }
     }
 
-    const std::vector<DeckKeywordPtr>&  KeywordContainer::getKeywordList(const std::string& keyword) const {
+    const std::vector<DeckKeywordConstPtr>&  KeywordContainer::getKeywordList(const std::string& keyword) const {
         if (hasKeyword(keyword)) {
-            const std::vector<DeckKeywordPtr>& keywordList = m_keywordMap.find(keyword)->second;
+            const std::vector<DeckKeywordConstPtr>& keywordList = m_keywordMap.find(keyword)->second;
             return keywordList;
         } else
             throw std::invalid_argument("Keyword: " + keyword + " is not found in the container");
     }
 
 
-    DeckKeywordPtr KeywordContainer::getKeyword(const std::string& keyword, size_t index) const {
-        const std::vector<DeckKeywordPtr>& keywordList = getKeywordList( keyword );
+    DeckKeywordConstPtr KeywordContainer::getKeyword(const std::string& keyword, size_t index) const {
+        const std::vector<DeckKeywordConstPtr>& keywordList = getKeywordList( keyword );
         if (index < keywordList.size())
             return keywordList[index];
         else
@@ -67,12 +67,12 @@ namespace Opm {
     }
 
 
-    DeckKeywordPtr KeywordContainer::getKeyword(const std::string& keyword) const {
-        const std::vector<DeckKeywordPtr>& keywordList = getKeywordList( keyword );
+    DeckKeywordConstPtr KeywordContainer::getKeyword(const std::string& keyword) const {
+        const std::vector<DeckKeywordConstPtr>& keywordList = getKeywordList( keyword );
         return keywordList.back();
     }
 
-    DeckKeywordPtr KeywordContainer::getKeyword(size_t index) const {
+    DeckKeywordConstPtr KeywordContainer::getKeyword(size_t index) const {
         if (index < m_keywordList.size())
             return m_keywordList[index];
         else
@@ -81,17 +81,17 @@ namespace Opm {
 
     size_t KeywordContainer::numKeywords(const std::string& keyword) const{
         if (hasKeyword(keyword)) {
-            const std::vector<DeckKeywordPtr>& keywordList = getKeywordList( keyword );
+            const std::vector<DeckKeywordConstPtr>& keywordList = getKeywordList( keyword );
             return keywordList.size();
         } else
             return 0;
     }
 
-    std::vector<DeckKeywordPtr>::iterator KeywordContainer::begin() {
+    std::vector<DeckKeywordConstPtr>::iterator KeywordContainer::begin() {
         return m_keywordList.begin();
     }
 
-    std::vector<DeckKeywordPtr>::iterator KeywordContainer::end() {
+    std::vector<DeckKeywordConstPtr>::iterator KeywordContainer::end() {
         return m_keywordList.end();
     }
 }
diff --git a/opm/parser/eclipse/Deck/KeywordContainer.hpp b/opm/parser/eclipse/Deck/KeywordContainer.hpp
index a9eec4efc..66d274216 100644
--- a/opm/parser/eclipse/Deck/KeywordContainer.hpp
+++ b/opm/parser/eclipse/Deck/KeywordContainer.hpp
@@ -22,20 +22,20 @@ namespace Opm {
         KeywordContainer();
         bool hasKeyword(const std::string& keyword) const;
         size_t size() const;
-        void addKeyword(DeckKeywordPtr keyword);
-        DeckKeywordPtr getKeyword(const std::string& keyword, size_t index) const;
-        DeckKeywordPtr getKeyword(const std::string& keyword) const;
-        DeckKeywordPtr      getKeyword(size_t index) const;
+        void addKeyword(DeckKeywordConstPtr keyword);
+        DeckKeywordConstPtr getKeyword(const std::string& keyword, size_t index) const;
+        DeckKeywordConstPtr getKeyword(const std::string& keyword) const;
+        DeckKeywordConstPtr      getKeyword(size_t index) const;
 
-        const std::vector<DeckKeywordPtr>&  getKeywordList(const std::string& keyword) const;
+        const std::vector<DeckKeywordConstPtr>&  getKeywordList(const std::string& keyword) const;
         size_t numKeywords(const std::string& keyword) const;
 
-        std::vector<DeckKeywordPtr>::iterator begin();
-        std::vector<DeckKeywordPtr>::iterator end();
+        std::vector<DeckKeywordConstPtr>::iterator begin();
+        std::vector<DeckKeywordConstPtr>::iterator end();
 
     private:
-        std::vector<DeckKeywordPtr> m_keywordList;
-        std::map<std::string, std::vector<DeckKeywordPtr> > m_keywordMap;
+        std::vector<DeckKeywordConstPtr> m_keywordList;
+        std::map<std::string, std::vector<DeckKeywordConstPtr> > m_keywordMap;
     };
     typedef std::shared_ptr<KeywordContainer> KeywordContainerPtr;
     typedef std::shared_ptr<const KeywordContainer> KeywordContainerConstPtr;
diff --git a/opm/parser/eclipse/Deck/Section.cpp b/opm/parser/eclipse/Deck/Section.cpp
index 956dcb2b3..3f3d6032a 100644
--- a/opm/parser/eclipse/Deck/Section.cpp
+++ b/opm/parser/eclipse/Deck/Section.cpp
@@ -77,11 +77,11 @@ namespace Opm {
         return m_keywords.hasKeyword(keyword);
     }
 
-    std::vector<DeckKeywordPtr>::iterator Section::begin() {
+    std::vector<DeckKeywordConstPtr>::iterator Section::begin() {
         return m_keywords.begin();
     }
 
-    std::vector<DeckKeywordPtr>::iterator Section::end() {
+    std::vector<DeckKeywordConstPtr>::iterator Section::end() {
         return m_keywords.end();
     }
 
diff --git a/opm/parser/eclipse/Deck/Section.hpp b/opm/parser/eclipse/Deck/Section.hpp
index 8370f310f..3549ca387 100644
--- a/opm/parser/eclipse/Deck/Section.hpp
+++ b/opm/parser/eclipse/Deck/Section.hpp
@@ -36,8 +36,8 @@ namespace Opm {
     public:
         Section(DeckConstPtr deck, const std::string& startKeyword);
         bool hasKeyword( const std::string& keyword ) const;
-        std::vector<DeckKeywordPtr>::iterator begin();
-        std::vector<DeckKeywordPtr>::iterator end();
+        std::vector<DeckKeywordConstPtr>::iterator begin();
+        std::vector<DeckKeywordConstPtr>::iterator end();
         DeckKeywordConstPtr getKeyword(const std::string& keyword, size_t index) const;
         DeckKeywordConstPtr getKeyword(const std::string& keyword) const;
         DeckKeywordConstPtr getKeyword(size_t index) const;
diff --git a/opm/parser/eclipse/Deck/tests/KeywordContainerTests.cpp b/opm/parser/eclipse/Deck/tests/KeywordContainerTests.cpp
index daee2c535..a6e0b30ac 100644
--- a/opm/parser/eclipse/Deck/tests/KeywordContainerTests.cpp
+++ b/opm/parser/eclipse/Deck/tests/KeywordContainerTests.cpp
@@ -104,7 +104,7 @@ BOOST_AUTO_TEST_CASE(getKeywordList_OK) {
     container->addKeyword(keyword2);
     container->addKeyword(keyword3);
 
-    const std::vector<DeckKeywordPtr>& keywordList = container->getKeywordList("TRULS");
+    const std::vector<DeckKeywordConstPtr>& keywordList = container->getKeywordList("TRULS");
     BOOST_CHECK_EQUAL( 3U , keywordList.size() );
 }
 
diff --git a/opm/parser/eclipse/IntegrationTests/ParseDENSITY.cpp b/opm/parser/eclipse/IntegrationTests/ParseDENSITY.cpp
index 3b70f894b..a83a7c817 100644
--- a/opm/parser/eclipse/IntegrationTests/ParseDENSITY.cpp
+++ b/opm/parser/eclipse/IntegrationTests/ParseDENSITY.cpp
@@ -41,7 +41,7 @@ BOOST_AUTO_TEST_CASE(ParseDENSITY) {
     ParserPtr parser(new Parser());
     boost::filesystem::path file("testdata/integration_tests/DENSITY/DENSITY1");
     DeckPtr deck =  parser->parseFile(file.string());
-    DeckKeywordPtr densityKw = deck->getKeyword("DENSITY" , 0);
+    DeckKeywordConstPtr densityKw = deck->getKeyword("DENSITY" , 0);
 
 
     BOOST_CHECK_EQUAL( 2U , densityKw->size());
diff --git a/opm/parser/eclipse/IntegrationTests/ParsePORO.cpp b/opm/parser/eclipse/IntegrationTests/ParsePORO.cpp
index 576693e70..943f903d1 100644
--- a/opm/parser/eclipse/IntegrationTests/ParsePORO.cpp
+++ b/opm/parser/eclipse/IntegrationTests/ParsePORO.cpp
@@ -40,7 +40,7 @@ BOOST_AUTO_TEST_CASE(ParsePOROandPERMX) {
     boost::filesystem::path poroFile("testdata/integration_tests/PORO/PORO1");
     DeckPtr deck =  parser->parseFile(poroFile.string());
     DeckKeywordConstPtr kw1 = deck->getKeyword("PORO" , 0);
-    DeckKeywordPtr kw2 = deck->getKeyword("PERMX" , 0);
+    DeckKeywordConstPtr kw2 = deck->getKeyword("PERMX" , 0);
 
     BOOST_CHECK_THROW( kw1->getIntData() , std::logic_error );
     BOOST_CHECK_THROW( kw1->getStringData() , std::logic_error );
diff --git a/opm/parser/eclipse/Parser/Parser.cpp b/opm/parser/eclipse/Parser/Parser.cpp
index 6a6fc6b5a..4fab4818d 100644
--- a/opm/parser/eclipse/Parser/Parser.cpp
+++ b/opm/parser/eclipse/Parser/Parser.cpp
@@ -476,7 +476,7 @@ namespace Opm {
     void Parser::applyUnitsToDeck(DeckPtr deck) const {
         deck->initUnitSystem();
         for (size_t index=0; index < deck->size(); ++index) {
-            DeckKeywordPtr deckKeyword = deck->getKeyword( index );
+            DeckKeywordConstPtr deckKeyword = deck->getKeyword( index );
             if (isRecognizedKeyword( deckKeyword->name())) {
                 ParserKeywordConstPtr parserKeyword = getParserKeywordFromDeckName( deckKeyword->name() );
                 if (parserKeyword->hasDimension()) {
diff --git a/opm/parser/eclipse/Parser/ParserKeyword.cpp b/opm/parser/eclipse/Parser/ParserKeyword.cpp
index 33bad217a..cfa3da38c 100644
--- a/opm/parser/eclipse/Parser/ParserKeyword.cpp
+++ b/opm/parser/eclipse/Parser/ParserKeyword.cpp
@@ -694,7 +694,7 @@ namespace Opm {
     }
 
 
-    void ParserKeyword::applyUnitsToDeck(std::shared_ptr<const Deck> deck , std::shared_ptr<DeckKeyword> deckKeyword) const {
+    void ParserKeyword::applyUnitsToDeck(std::shared_ptr<const Deck> deck , std::shared_ptr<const DeckKeyword> deckKeyword) const {
         std::shared_ptr<const ParserRecord> parserRecord = getRecord();
         for (size_t index = 0; index < deckKeyword->size(); index++) {
             std::shared_ptr<const DeckRecord> deckRecord = deckKeyword->getRecord(index);
diff --git a/opm/parser/eclipse/Parser/ParserKeyword.hpp b/opm/parser/eclipse/Parser/ParserKeyword.hpp
index 7ff47fee4..eda1df01f 100644
--- a/opm/parser/eclipse/Parser/ParserKeyword.hpp
+++ b/opm/parser/eclipse/Parser/ParserKeyword.hpp
@@ -142,7 +142,7 @@ namespace Opm {
         bool isDataKeyword() const;
         bool equal(const ParserKeyword& other) const;
         void inlineNew(std::ostream& os , const std::string& lhs, const std::string& indent) const;
-        void applyUnitsToDeck(std::shared_ptr<const Deck> deck , std::shared_ptr<DeckKeyword> deckKeyword) const;
+        void applyUnitsToDeck(std::shared_ptr<const Deck> deck , std::shared_ptr<const DeckKeyword> deckKeyword) const;
     private:
         std::pair<std::string,std::string> m_sizeDefinitionPair;
         std::string m_name;