diff --git a/pkg/runtime/assertions.go b/pkg/runtime/assertions.go
index 0a808b08..438a0c22 100644
--- a/pkg/runtime/assertions.go
+++ b/pkg/runtime/assertions.go
@@ -65,6 +65,19 @@ func AssertBoolean(input Value) error {
 	return nil
 }
 
+func AssertCollection(input Value) error {
+	_, ok := input.(Collection)
+
+	if !ok {
+		return TypeErrorOf(
+			input,
+			TypeCollection,
+		)
+	}
+
+	return nil
+}
+
 func AssertArray(input Value) error {
 	_, ok := input.(*Array)
 
diff --git a/pkg/runtime/casting.go b/pkg/runtime/casting.go
index f53a9006..b9036c9b 100644
--- a/pkg/runtime/casting.go
+++ b/pkg/runtime/casting.go
@@ -100,6 +100,16 @@ func SafeCastDateTime(input Value, fallback DateTime) DateTime {
 	return fallback
 }
 
+func CastCollection(input Value) (Collection, error) {
+	arr, ok := input.(Collection)
+
+	if ok {
+		return arr, nil
+	}
+
+	return nil, TypeErrorOf(input, TypeCollection)
+}
+
 func CastList(input Value) (List, error) {
 	arr, ok := input.(List)
 
diff --git a/pkg/runtime/type.go b/pkg/runtime/type.go
index fe2d5b0f..2bfba67f 100644
--- a/pkg/runtime/type.go
+++ b/pkg/runtime/type.go
@@ -37,6 +37,7 @@ const (
 	TypeBinary   = Type("binary")
 
 	// Interfaces
+	TypeCollection = Type("collection")
 	TypeList       = Type("list")
 	TypeMap        = Type("map")
 	TypeIndexed    = Type("indexed")
diff --git a/pkg/stdlib/collections/count_distinct.go b/pkg/stdlib/collections/count_distinct.go
new file mode 100644
index 00000000..f7c4958f
--- /dev/null
+++ b/pkg/stdlib/collections/count_distinct.go
@@ -0,0 +1,43 @@
+package collections
+
+import (
+	"context"
+	"github.com/MontFerret/ferret/pkg/runtime"
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+)
+
+// COUNT_DISTINCT computes the number of distinct elements in the given collection and returns the count as an integer.
+func CountDistinct(ctx context.Context, args ...core.Value) (core.Value, error) {
+	if err := runtime.ValidateArgs(args, 1, 1); err != nil {
+		return runtime.None, err
+	}
+
+	collection, err := runtime.CastCollection(args[0])
+
+	if err != nil {
+		return runtime.ZeroInt, err
+	}
+
+	// TODO: Use storage backend
+	hashmap := map[uint64]bool{}
+	var res runtime.Int
+
+	err = runtime.ForEach(ctx, collection, func(c context.Context, value, idx runtime.Value) (runtime.Boolean, error) {
+		hash := value.Hash()
+
+		_, exists := hashmap[hash]
+
+		if !exists {
+			hashmap[hash] = true
+			res++
+		}
+
+		return true, nil
+	})
+
+	if err != nil {
+		return runtime.ZeroInt, err
+	}
+
+	return res, nil
+}
diff --git a/pkg/stdlib/collections/lib.go b/pkg/stdlib/collections/lib.go
index 6c7bc380..d91f58ab 100644
--- a/pkg/stdlib/collections/lib.go
+++ b/pkg/stdlib/collections/lib.go
@@ -7,7 +7,8 @@ import (
 func RegisterLib(ns runtime.Namespace) error {
 	return ns.RegisterFunctions(
 		runtime.NewFunctionsFromMap(map[string]runtime.Function{
-			"INCLUDES": Includes,
-			"REVERSE":  Reverse,
+			"COUNT_DISTINCT": CountDistinct,
+			"INCLUDES":       Includes,
+			"REVERSE":        Reverse,
 		}))
 }
diff --git a/pkg/stdlib/math/max.go b/pkg/stdlib/math/max.go
index be3c6be8..ba44eb40 100644
--- a/pkg/stdlib/math/max.go
+++ b/pkg/stdlib/math/max.go
@@ -30,19 +30,13 @@ func Max(ctx context.Context, args ...runtime.Value) (runtime.Value, error) {
 		return runtime.None, nil
 	}
 
-	var max float64
+	var res float64
 
 	err = arr.ForEach(ctx, func(c context.Context, value runtime.Value, idx runtime.Int) (runtime.Boolean, error) {
-		err = runtime.AssertNumber(value)
-
-		if err != nil {
-			return false, nil
-		}
-
 		fv := toFloat(value)
 
-		if fv > max {
-			max = fv
+		if fv > res {
+			res = fv
 		}
 
 		return true, nil
@@ -52,5 +46,5 @@ func Max(ctx context.Context, args ...runtime.Value) (runtime.Value, error) {
 		return runtime.None, nil
 	}
 
-	return runtime.NewFloat(max), nil
+	return runtime.NewFloat(res), nil
 }
diff --git a/pkg/stdlib/math/min.go b/pkg/stdlib/math/min.go
index 149ba604..e396e817 100644
--- a/pkg/stdlib/math/min.go
+++ b/pkg/stdlib/math/min.go
@@ -30,19 +30,13 @@ func Min(ctx context.Context, args ...runtime.Value) (runtime.Value, error) {
 		return runtime.None, nil
 	}
 
-	var min float64
+	var res float64
 
 	err = arr.ForEach(ctx, func(c context.Context, value runtime.Value, idx runtime.Int) (runtime.Boolean, error) {
-		err = runtime.AssertNumber(value)
-
-		if err != nil {
-			return false, nil
-		}
-
 		fv := toFloat(value)
 
-		if min > fv || idx == 0 {
-			min = fv
+		if res > fv || idx == 0 {
+			res = fv
 		}
 
 		return true, nil
@@ -52,5 +46,5 @@ func Min(ctx context.Context, args ...runtime.Value) (runtime.Value, error) {
 		return runtime.None, nil
 	}
 
-	return runtime.NewFloat(min), nil
+	return runtime.NewFloat(res), nil
 }
diff --git a/test/integration/vm/vm_for_collect_agg_test.go b/test/integration/vm/vm_for_collect_agg_test.go
index 4c22026a..60e01393 100644
--- a/test/integration/vm/vm_for_collect_agg_test.go
+++ b/test/integration/vm/vm_for_collect_agg_test.go
@@ -39,7 +39,7 @@ func TestCollectAggregate(t *testing.T) {
 				}
 		`, []any{
 			map[string]any{"gender": "f", "minAge": 25, "maxAge": 25},
-			map[string]any{"gender": "m", "minAge": nil, "maxAge": nil},
+			map[string]any{"gender": "m", "minAge": 0, "maxAge": 0},
 		}, "Should handle null values in aggregation"),
 		CaseArray(`
 LET users = [
@@ -204,7 +204,7 @@ FOR u IN users
 				"gender":          "m",
 				"activeCount":     2,
 				"marriedCount":    2,
-				"highSalaryCount": 2,
+				"highSalaryCount": 3,
 			},
 		}, "Should aggregate with conditional expressions"),
 		CaseArray(`
@@ -498,7 +498,7 @@ FOR u IN users
 			]
 			FOR u IN users
 				COLLECT AGGREGATE 
-					allSkills = UNION(u.skills),
+					allSkills = UNION_DISTINCT(u.skills, u.skills),
 					uniqueSkillCount = COUNT_DISTINCT(u.skills)
 				RETURN {
 					allSkills: SORTED(allSkills),
@@ -506,8 +506,13 @@ FOR u IN users
 				}
 		`, []any{
 			map[string]any{
-				"allSkills":        []any{"C++", "Go", "Java", "JavaScript", "Python", "Rust", "TypeScript"},
-				"uniqueSkillCount": 7,
+				"allSkills": []any{
+					[]any{"Go", "Rust"},
+					[]any{"JavaScript", "TypeScript"},
+					[]any{"Java", "C++", "Python"},
+					[]any{"JavaScript", "Python", "Go"},
+				},
+				"uniqueSkillCount": 4,
 			},
 		}, "Should aggregate with array operations"),
 	})