diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/CalcEngineException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/CalcEngineException.cs
index 962b1c6..1e7f1f7 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/CalcEngineException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/CalcEngineException.cs
@@ -2,7 +2,7 @@
 
 namespace ClosedXML.Excel.CalcEngine.Exceptions
 {
-    internal abstract class CalcEngineException : ArgumentException
+    public abstract class CalcEngineException : ArgumentException
     {
         protected CalcEngineException()
             : base()
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/CellReferenceException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/CellReferenceException.cs
index f0fd88c..91e219e 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/CellReferenceException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/CellReferenceException.cs
@@ -9,17 +9,17 @@
     /// Corresponds to the #REF! error in Excel
     /// </summary>
     /// <seealso cref="ClosedXML.Excel.CalcEngine.Exceptions.CalcEngineException" />
-    internal class CellReferenceException : CalcEngineException
+    public class CellReferenceException : CalcEngineException
     {
-        public CellReferenceException()
+        internal CellReferenceException()
             : base()
         { }
 
-        public CellReferenceException(string message)
+        internal CellReferenceException(string message)
             : base(message)
         { }
 
-        public CellReferenceException(string message, Exception innerException)
+        internal CellReferenceException(string message, Exception innerException)
             : base(message, innerException)
         { }
 
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/CellValueException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/CellValueException.cs
index 0716353..ad129dc 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/CellValueException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/CellValueException.cs
@@ -9,17 +9,17 @@
     /// Corresponds to the #VALUE! error in Excel
     /// </summary>
     /// <seealso cref="ClosedXML.Excel.CalcEngine.Exceptions.CalcEngineException" />
-    internal class CellValueException : CalcEngineException
+    public class CellValueException : CalcEngineException
     {
-        public CellValueException()
+        internal CellValueException()
             : base()
         { }
 
-        public CellValueException(string message)
+        internal CellValueException(string message)
             : base(message)
         { }
 
-        public CellValueException(string message, Exception innerException)
+        internal CellValueException(string message, Exception innerException)
             : base(message, innerException)
         { }
     }
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/DivisionByZeroException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/DivisionByZeroException.cs
index 53e2ed1..8bc6b7b 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/DivisionByZeroException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/DivisionByZeroException.cs
@@ -8,19 +8,19 @@
     /// Corresponds to the #DIV/0! error in Excel
     /// </summary>
     /// <seealso cref="System.DivideByZeroException" />
-    internal class DivisionByZeroException : CalcEngineException
+    public class DivisionByZeroException : CalcEngineException
     {
-        public DivisionByZeroException()
+        internal DivisionByZeroException()
             : base()
         { }
 
-        public DivisionByZeroException(string message)
+        internal DivisionByZeroException(string message)
             : base(message)
         { }
 
-        public DivisionByZeroException(string message, Exception innerException)
+        internal DivisionByZeroException(string message, Exception innerException)
             : base(message, innerException)
         { }
 
     }
-}
\ No newline at end of file
+}
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/NameNotRecognizedException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/NameNotRecognizedException.cs
index 0f51e56..7a93075 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/NameNotRecognizedException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/NameNotRecognizedException.cs
@@ -9,17 +9,17 @@
     /// Corresponds to the #NAME? error in Excel
     /// </summary>
     /// <seealso cref="System.ApplicationException" />
-    internal class NameNotRecognizedException : CalcEngineException
+    public class NameNotRecognizedException : CalcEngineException
     {
-        public NameNotRecognizedException()
+        internal NameNotRecognizedException()
             : base()
         { }
 
-        public NameNotRecognizedException(string message)
+        internal NameNotRecognizedException(string message)
             : base(message)
         { }
 
-        public NameNotRecognizedException(string message, Exception innerException)
+        internal NameNotRecognizedException(string message, Exception innerException)
             : base(message, innerException)
         { }
 
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/NoValueAvailableException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/NoValueAvailableException.cs
index 0e97fe5..318fb9a 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/NoValueAvailableException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/NoValueAvailableException.cs
@@ -9,19 +9,19 @@
     /// Corresponds to the #N/A error in Excel.
     /// </summary>
     /// <seealso cref="System.ApplicationException" />
-    internal class NoValueAvailableException : CalcEngineException
+    public class NoValueAvailableException : CalcEngineException
     {
-        public NoValueAvailableException()
+        internal NoValueAvailableException()
             : base()
         { }
 
-        public NoValueAvailableException(string message)
+        internal NoValueAvailableException(string message)
             : base(message)
         { }
 
-        public NoValueAvailableException(string message, Exception innerException)
+        internal NoValueAvailableException(string message, Exception innerException)
             : base(message, innerException)
         { }
 
     }
-}
\ No newline at end of file
+}
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/NullValueException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/NullValueException.cs
index d3153d7..5cc74bc 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/NullValueException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/NullValueException.cs
@@ -9,17 +9,17 @@
     /// Corresponds to the #NULL! error in Excel
     /// </summary>
     /// <seealso cref="ClosedXML.Excel.CalcEngine.Exceptions.CalcEngineException" />
-    internal class NullValueException : CalcEngineException
+    public class NullValueException : CalcEngineException
     {
-        public NullValueException()
+        internal NullValueException()
             : base()
         { }
 
-        public NullValueException(string message)
+        internal NullValueException(string message)
             : base(message)
         { }
 
-        public NullValueException(string message, Exception innerException)
+        internal NullValueException(string message, Exception innerException)
             : base(message, innerException)
         { }
 
diff --git a/ClosedXML/Excel/CalcEngine/Exceptions/NumberException.cs b/ClosedXML/Excel/CalcEngine/Exceptions/NumberException.cs
index 4ce87d0..7d248f5 100644
--- a/ClosedXML/Excel/CalcEngine/Exceptions/NumberException.cs
+++ b/ClosedXML/Excel/CalcEngine/Exceptions/NumberException.cs
@@ -9,17 +9,17 @@
     /// Corresponds to the #NUM! error in Excel
     /// </summary>
     /// <seealso cref="ClosedXML.Excel.CalcEngine.Exceptions.CalcEngineException" />
-    internal class NumberException : CalcEngineException
+    public class NumberException : CalcEngineException
     {
-        public NumberException()
+        internal NumberException()
             : base()
         { }
 
-        public NumberException(string message)
+        internal NumberException(string message)
             : base(message)
         { }
 
-        public NumberException(string message, Exception innerException)
+        internal NumberException(string message, Exception innerException)
             : base(message, innerException)
         { }