diff --git a/MarkMpn.Sql4Cds.Engine.Tests/AdoProviderTests.cs b/MarkMpn.Sql4Cds.Engine.Tests/AdoProviderTests.cs
index 35cff7b2..c860a443 100644
--- a/MarkMpn.Sql4Cds.Engine.Tests/AdoProviderTests.cs
+++ b/MarkMpn.Sql4Cds.Engine.Tests/AdoProviderTests.cs
@@ -2930,7 +2930,7 @@ public void ErrorOnTruncateGuid()
         }
 
         [TestMethod]
-        public void ErrorOnTruncateEntityReferenc()
+        public void ErrorOnTruncateEntityReference()
         {
             using (var con = new Sql4CdsConnection(_localDataSources))
             using (var cmd = con.CreateCommand())
@@ -2951,5 +2951,33 @@ public void ErrorOnTruncateEntityReferenc()
                 }
             }
         }
+
+        [TestMethod]
+        public void NestedPrimaryFunctions()
+        {
+            using (var con = new Sql4CdsConnection(_localDataSources))
+            using (var cmd = con.CreateCommand())
+            {
+                cmd.CommandText = "INSERT INTO account (name) VALUES ('Data8')";
+                cmd.ExecuteNonQuery();
+                cmd.CommandText = "INSERT INTO account (name) VALUES (null)";
+                cmd.ExecuteNonQuery();
+
+                cmd.CommandText = "SELECT name, MAX(IIF(name = 'Data8', COALESCE(turnover, -1), 0)) FROM account GROUP BY name";
+
+                using (var reader = cmd.ExecuteReader())
+                {
+                    Assert.IsTrue(reader.Read());
+                    Assert.IsTrue(reader.IsDBNull(0));
+                    Assert.AreEqual(0, reader.GetDecimal(1));
+
+                    Assert.IsTrue(reader.Read());
+                    Assert.AreEqual("Data8", reader.GetString(0));
+                    Assert.AreEqual(-1, reader.GetDecimal(1));
+
+                    Assert.IsFalse(reader.Read());
+                }
+            }
+        }
     }
 }
diff --git a/MarkMpn.Sql4Cds.Engine/Visitors/ReplacePrimaryFunctionsVisitor.cs b/MarkMpn.Sql4Cds.Engine/Visitors/ReplacePrimaryFunctionsVisitor.cs
index e815d833..cffedff8 100644
--- a/MarkMpn.Sql4Cds.Engine/Visitors/ReplacePrimaryFunctionsVisitor.cs
+++ b/MarkMpn.Sql4Cds.Engine/Visitors/ReplacePrimaryFunctionsVisitor.cs
@@ -31,6 +31,7 @@ protected override ScalarExpression ReplaceExpression(ScalarExpression expressio
                         ThenExpression = expr
                     });
 
+                caseExpr.Accept(this);
                 return caseExpr;
             }
 
@@ -42,13 +43,14 @@ protected override ScalarExpression ReplaceExpression(ScalarExpression expressio
                     {
                         new SearchedWhenClause
                         {
-                            WhenExpression = iif.Predicate,
-                            ThenExpression = iif.ThenExpression
+                            WhenExpression = iif.Predicate.Clone(),
+                            ThenExpression = iif.ThenExpression.Clone()
                         }
                     },
-                    ElseExpression = iif.ElseExpression
+                    ElseExpression = iif.ElseExpression.Clone()
                 };
 
+                caseExpr.Accept(this);
                 return caseExpr;
             }
 
@@ -60,8 +62,9 @@ protected override ScalarExpression ReplaceExpression(ScalarExpression expressio
                 };
 
                 foreach (var param in left.Parameters)
-                    leftFunc.Parameters.Add(param);
+                    leftFunc.Parameters.Add(param.Clone());
 
+                leftFunc.Accept(this);
                 return leftFunc;
             }
 
@@ -75,16 +78,17 @@ protected override ScalarExpression ReplaceExpression(ScalarExpression expressio
                         {
                             WhenExpression = new BooleanComparisonExpression
                             {
-                                ComparisonType = BooleanComparisonType.Equals,
                                 FirstExpression = nullif.FirstExpression.Clone(),
-                                SecondExpression = nullif.SecondExpression
+                                ComparisonType = BooleanComparisonType.Equals,
+                                SecondExpression = nullif.SecondExpression.Clone()
                             },
                             ThenExpression = new NullLiteral()
                         }
                     },
-                    ElseExpression = nullif.FirstExpression
+                    ElseExpression = nullif.FirstExpression.Clone()
                 };
 
+                caseExpr.Accept(this);
                 return caseExpr;
             }
 
@@ -96,8 +100,9 @@ protected override ScalarExpression ReplaceExpression(ScalarExpression expressio
                 };
 
                 foreach (var param in right.Parameters)
-                    rightFunc.Parameters.Add(param);
+                    rightFunc.Parameters.Add(param.Clone());
 
+                rightFunc.Accept(this);
                 return rightFunc;
             }
 
@@ -126,9 +131,9 @@ protected override BooleanExpression ReplaceExpression(BooleanExpression express
                     {
                         FirstExpression = new BooleanComparisonExpression
                         {
-                            FirstExpression = between.FirstExpression,
+                            FirstExpression = between.FirstExpression.Clone(),
                             ComparisonType = between.TernaryExpressionType == BooleanTernaryExpressionType.Between ? BooleanComparisonType.GreaterThanOrEqualTo : BooleanComparisonType.LessThan,
-                            SecondExpression = between.SecondExpression,
+                            SecondExpression = between.SecondExpression.Clone(),
 
                             FirstTokenIndex = between.FirstTokenIndex,
                             LastTokenIndex = between.LastTokenIndex,
@@ -137,9 +142,9 @@ protected override BooleanExpression ReplaceExpression(BooleanExpression express
                         BinaryExpressionType = between.TernaryExpressionType == BooleanTernaryExpressionType.Between ? BooleanBinaryExpressionType.And : BooleanBinaryExpressionType.Or,
                         SecondExpression = new BooleanComparisonExpression
                         {
-                            FirstExpression = between.FirstExpression,
+                            FirstExpression = between.FirstExpression.Clone(),
                             ComparisonType = between.TernaryExpressionType == BooleanTernaryExpressionType.Between ? BooleanComparisonType.LessThanOrEqualTo : BooleanComparisonType.GreaterThan,
-                            SecondExpression = between.ThirdExpression,
+                            SecondExpression = between.ThirdExpression.Clone(),
 
                             FirstTokenIndex = between.FirstTokenIndex,
                             LastTokenIndex = between.LastTokenIndex,
@@ -156,6 +161,7 @@ protected override BooleanExpression ReplaceExpression(BooleanExpression express
                     ScriptTokenStream = between.ScriptTokenStream
                 };
 
+                converted.Accept(this);
                 return converted;
             }