diff --git a/processing/src/main/java/org/apache/druid/math/expr/Function.java b/processing/src/main/java/org/apache/druid/math/expr/Function.java
index 48bc0570aaa3..d62d632f40b7 100644
--- a/processing/src/main/java/org/apache/druid/math/expr/Function.java
+++ b/processing/src/main/java/org/apache/druid/math/expr/Function.java
@@ -622,11 +622,10 @@ public ExprEval apply(List<Expr> args, Expr.ObjectBinding bindings)
         ExprEval<?> exprEval = expr.eval(bindings);
         ExpressionType exprType = exprEval.type();
 
-        if (isValidType(exprType)) {
-          outputType = ExpressionTypeConversion.function(outputType, exprType);
-        }
-
         if (exprEval.value() != null) {
+          if (isValidType(exprType)) {
+            outputType = ExpressionTypeConversion.function(outputType, exprType);
+          }
           evals.add(exprEval);
         }
       }
diff --git a/processing/src/test/java/org/apache/druid/math/expr/FunctionTest.java b/processing/src/test/java/org/apache/druid/math/expr/FunctionTest.java
index d6143fd1fa15..56b3583031f0 100644
--- a/processing/src/test/java/org/apache/druid/math/expr/FunctionTest.java
+++ b/processing/src/test/java/org/apache/druid/math/expr/FunctionTest.java
@@ -677,6 +677,7 @@ public void testGreatest()
     assertExpr("greatest()", null);
     assertExpr("greatest(null, null)", null);
     assertExpr("greatest(1, null, 'A')", "A");
+    assertExpr("greatest(1.0, 1, null)", 1.0);
   }
 
   @Test
@@ -703,6 +704,7 @@ public void testLeast()
     assertExpr("least()", null);
     assertExpr("least(null, null)", null);
     assertExpr("least(1, null, 'A')", "1");
+    assertExpr("least(1.0, 1, null)", 1.0);
   }
 
   @Test
diff --git a/sql/src/test/java/org/apache/druid/sql/calcite/expression/GreatestExpressionTest.java b/sql/src/test/java/org/apache/druid/sql/calcite/expression/GreatestExpressionTest.java
index f1a5a869a192..893b54499348 100644
--- a/sql/src/test/java/org/apache/druid/sql/calcite/expression/GreatestExpressionTest.java
+++ b/sql/src/test/java/org/apache/druid/sql/calcite/expression/GreatestExpressionTest.java
@@ -214,7 +214,7 @@ public void testDecimal()
   }
 
   @Test
-  public void testDecimalWithNullShouldReturnString()
+  public void testDecimalWithNullShouldNotReturnString()
   {
     testExpression(
         Arrays.asList(
@@ -227,7 +227,7 @@ public void testDecimalWithNullShouldReturnString()
             null,
             3.4
         ),
-        "3.4"
+        3.4
     );
   }
   @Test
diff --git a/sql/src/test/java/org/apache/druid/sql/calcite/expression/LeastExpressionTest.java b/sql/src/test/java/org/apache/druid/sql/calcite/expression/LeastExpressionTest.java
index eaec03c00c87..e2d1bbf306ea 100644
--- a/sql/src/test/java/org/apache/druid/sql/calcite/expression/LeastExpressionTest.java
+++ b/sql/src/test/java/org/apache/druid/sql/calcite/expression/LeastExpressionTest.java
@@ -214,7 +214,7 @@ public void testDecimal()
   }
 
   @Test
-  public void testDecimalWithNullShouldReturnString()
+  public void testDecimalWithNullShouldNotReturnString()
   {
     testExpression(
         Arrays.asList(
@@ -227,7 +227,7 @@ public void testDecimalWithNullShouldReturnString()
             3.4,
             null
         ),
-        "1.2"
+        1.2
     );
   }