diff --git a/core/src/main/java/org/apache/calcite/rel/rules/AggregateReduceFunctionsRule.java b/core/src/main/java/org/apache/calcite/rel/rules/AggregateReduceFunctionsRule.java
index ac40cc9101a4..91cc550b3f4a 100644
--- a/core/src/main/java/org/apache/calcite/rel/rules/AggregateReduceFunctionsRule.java
+++ b/core/src/main/java/org/apache/calcite/rel/rules/AggregateReduceFunctionsRule.java
@@ -968,7 +968,8 @@ public interface Config extends RelRule.Config {
             .addAll(SqlKind.AVG_AGG_FUNCTIONS)
             .addAll(SqlKind.COVAR_AVG_AGG_FUNCTIONS)
             .add(SqlKind.SUM)
-            .build();
+            .build().stream().filter(k -> k != SqlKind.REGR_COUNT)
+            .collect(ImmutableSet.toImmutableSet());
 
     @Override default AggregateReduceFunctionsRule toRule() {
       return new AggregateReduceFunctionsRule(this);
diff --git a/core/src/main/java/org/apache/calcite/rex/RexBuilder.java b/core/src/main/java/org/apache/calcite/rex/RexBuilder.java
index 95030b5b9053..25e76ea740dd 100644
--- a/core/src/main/java/org/apache/calcite/rex/RexBuilder.java
+++ b/core/src/main/java/org/apache/calcite/rex/RexBuilder.java
@@ -39,7 +39,6 @@
 import org.apache.calcite.sql.SqlTimeLiteral;
 import org.apache.calcite.sql.SqlTimestampLiteral;
 import org.apache.calcite.sql.SqlUtil;
-import org.apache.calcite.sql.fun.SqlCountAggFunction;
 import org.apache.calcite.sql.fun.SqlLibraryOperators;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
 import org.apache.calcite.sql.parser.SqlParserPos;
@@ -388,7 +387,7 @@ public RexNode addAggCall(AggregateCall aggCall, int groupCount,
       List<AggregateCall> aggCalls,
       Map<AggregateCall, RexNode> aggCallMapping,
       IntPredicate isNullable) {
-    if (aggCall.getAggregation() instanceof SqlCountAggFunction
+    if (aggCall.getAggregation().getKind() == SqlKind.COUNT
         && !aggCall.isDistinct()) {
       final List<Integer> args = aggCall.getArgList();
       final List<Integer> nullableArgs = nullableArgs(args, isNullable);
diff --git a/core/src/main/java/org/apache/calcite/sql/fun/SqlCountAggFunction.java b/core/src/main/java/org/apache/calcite/sql/fun/SqlCountAggFunction.java
index 3007ad346593..fe5c41f3a4d0 100644
--- a/core/src/main/java/org/apache/calcite/sql/fun/SqlCountAggFunction.java
+++ b/core/src/main/java/org/apache/calcite/sql/fun/SqlCountAggFunction.java
@@ -55,9 +55,14 @@ public SqlCountAggFunction(String name) {
 
   public SqlCountAggFunction(String name,
       SqlOperandTypeChecker sqlOperandTypeChecker) {
-    super(name, null, SqlKind.COUNT, ReturnTypes.BIGINT, null,
-        sqlOperandTypeChecker, SqlFunctionCategory.NUMERIC, false, false,
-        Optionality.FORBIDDEN);
+    this(name, sqlOperandTypeChecker, SqlKind.COUNT);
+  }
+
+  public SqlCountAggFunction(String name,
+      SqlOperandTypeChecker sqlOperandTypeChecker,
+      SqlKind sqlKind) {
+    super(name, null, sqlKind, ReturnTypes.BIGINT, null, sqlOperandTypeChecker,
+        SqlFunctionCategory.NUMERIC, false, false, Optionality.FORBIDDEN);
   }
 
   //~ Methods ----------------------------------------------------------------
diff --git a/core/src/main/java/org/apache/calcite/sql/fun/SqlRegrCountAggFunction.java b/core/src/main/java/org/apache/calcite/sql/fun/SqlRegrCountAggFunction.java
index 28023ed83d29..976e08596d07 100644
--- a/core/src/main/java/org/apache/calcite/sql/fun/SqlRegrCountAggFunction.java
+++ b/core/src/main/java/org/apache/calcite/sql/fun/SqlRegrCountAggFunction.java
@@ -29,7 +29,7 @@
  */
 public class SqlRegrCountAggFunction extends SqlCountAggFunction {
   public SqlRegrCountAggFunction(SqlKind kind) {
-    super("REGR_COUNT", OperandTypes.NUMERIC_NUMERIC);
+    super("REGR_COUNT", OperandTypes.NUMERIC_NUMERIC, kind);
     checkArgument(SqlKind.REGR_COUNT == kind, "unsupported sql kind: " + kind);
   }
 }