diff --git a/config.go b/config.go
index 4909d8c..8ce2da3 100644
--- a/config.go
+++ b/config.go
@@ -20,7 +20,7 @@ const (
 	NullType
 	SubstitutionType
 	ConcatenationType
-	stringWithAlternativeType
+	valueWithAlternativeType
 )
 
 // Config stores the root of the configuration tree
@@ -287,19 +287,19 @@ func (s String) Type() Type           { return StringType }
 func (s String) String() string       { return strings.Trim(string(s), `"`) }
 func (s String) isConcatenable() bool { return true }
 
-// stringWithAlternative represents a string value with Substitution which might override the original string value
-type stringWithAlternative struct {
-	value       String
+// valueWithAlternative represents a value with Substitution which might override the original value
+type valueWithAlternative struct {
+	value       Value
 	alternative *Substitution
 }
 
-func (s *stringWithAlternative) Type() Type { return stringWithAlternativeType }
+func (s *valueWithAlternative) Type() Type { return valueWithAlternativeType }
 
-func (s *stringWithAlternative) String() string {
+func (s *valueWithAlternative) String() string {
 	return fmt.Sprintf("(%s | %s)", s.value, s.alternative.String())
 }
 
-func (s *stringWithAlternative) isConcatenable() bool { return false }
+func (s *valueWithAlternative) isConcatenable() bool { return false }
 
 // Object represents an object node in the configuration tree
 type Object map[string]Value
diff --git a/config_test.go b/config_test.go
index a7182bc..980a1ec 100644
--- a/config_test.go
+++ b/config_test.go
@@ -442,10 +442,10 @@ func TestSubstitution_String(t *testing.T) {
 	})
 }
 
-func TestStringWithAlternative_String(t *testing.T) {
-	t.Run("return the string of string with alternative", func(t *testing.T) {
+func TestValueWithAlternative_String(t *testing.T) {
+	t.Run("return the string of valueWithAlternative", func(t *testing.T) {
 		substitution := Substitution{path: "a", optional: false}
-		withAlt := stringWithAlternative{value: "value", alternative: &substitution}
+		withAlt := valueWithAlternative{value: String("value"), alternative: &substitution}
 		got := withAlt.String()
 		assertEquals(t, got, "(value | ${a})")
 	})
diff --git a/parser.go b/parser.go
index 763246e..f2da1be 100644
--- a/parser.go
+++ b/parser.go
@@ -169,8 +169,8 @@ func processSubstitution(root Object, value Value, resolveFunc func(value Value)
 		}
 		resolveFunc(processed)
 		return nil
-	} else if valueType == stringWithAlternativeType {
-		withAlternative := value.(*stringWithAlternative)
+	} else if valueType == valueWithAlternativeType {
+		withAlternative := value.(*valueWithAlternative)
 		if withAlternative.alternative != nil {
 			processed, err := processSubstitutionType(root, withAlternative.alternative)
 			if err != nil {
@@ -306,16 +306,10 @@ func (p *parser) extractObject(isSubObject ...bool) (Object, error) {
 					(existingValue.Type() == ObjectType && value.Type() == SubstitutionType) ||
 					(existingValue.Type() == SubstitutionType && value.Type() == ObjectType) {
 					value = concatenation{existingValue, value}
-				} else if existingValue.Type() == StringType && value.Type() == SubstitutionType {
-					value = &stringWithAlternative{
-						value:       existingValue.(String),
-						alternative: value.(*Substitution),
-					}
-				} else if existingValue.Type() == stringWithAlternativeType && value.Type() == SubstitutionType {
-					value = &stringWithAlternative{
-						value:       existingValue.(*stringWithAlternative).value,
-						alternative: value.(*Substitution),
-					}
+				} else if existingValue.Type() == valueWithAlternativeType && value.Type() == SubstitutionType {
+					value = &valueWithAlternative{value: existingValue, alternative: value.(*Substitution)}
+				} else if value.Type() == SubstitutionType {
+					value = &valueWithAlternative{value: existingValue, alternative: value.(*Substitution)}
 				}
 			}
 
diff --git a/parser_test.go b/parser_test.go
index 3b39f9a..ce6b6b7 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -365,6 +364,20 @@ func TestExtractObject(t *testing.T) {
 		assertDeepEqual(t, got, expected)
 	})
 
+	t.Run("return valueWithAlternative object if the current value (after colon separator) is substitution and the existing value is neither a substitution nor object", func(t *testing.T) {
+		parser := newParser(strings.NewReader("{a:1,a:${?b}}"))
+		parser.advance()
+		expected := Object{
+			"a": &valueWithAlternative{
+				value:       Int(1),
+				alternative: &Substitution{path: "b", optional: true},
+			},
+		}
+		got, err := parser.extractObject()
+		assertNoError(t, err)
+		assertDeepEqual(t, got, expected)
+	})
+
 	t.Run("override the existing value if the current value (after colon separator) is object and there is an existing non-object with the same key", func(t *testing.T) {
 		parser := newParser(strings.NewReader("{a:1,a:{c:2}}"))
 		parser.advance()
@@ -564,7 +577,7 @@ func TestResolveSubstitutions(t *testing.T) {
 		testEnv := "TEST_ENV"
 		testEnvValue := "test"
 		envSubstitution := &Substitution{path: testEnv, optional: false}
-		staticWithEnv := &stringWithAlternative{value: "static", alternative: envSubstitution}
+		staticWithEnv := &valueWithAlternative{value: String("static"), alternative: envSubstitution}
 		object := Object{"a": staticWithEnv}
 		err := os.Setenv(testEnv, testEnvValue)
 		assertNoError(t, err)
@@ -582,7 +595,7 @@ func TestResolveSubstitutions(t *testing.T) {
 	t.Run("resolve to the static value if substitution path does not exist and environment variable is not set and default value was not provided", func(t *testing.T) {
 		defaultValue := String("default")
 		envSubstitution := &Substitution{path: "TEST_ENV", optional: true}
-		staticWithEnv := &stringWithAlternative{value: defaultValue, alternative: envSubstitution}
+		staticWithEnv := &valueWithAlternative{value: defaultValue, alternative: envSubstitution}
 		object := Object{"a": staticWithEnv}
 		err := resolveSubstitutions(object)
 		assertNoError(t, err)
@@ -595,7 +608,7 @@ func TestResolveSubstitutions(t *testing.T) {
 	t.Run("return an error if cannot find required substitution and default value was provided", func(t *testing.T) {
 		defaultValue := String("default")
 		envSubstitution := &Substitution{path: "TEST_ENV", optional: false}
-		staticWithEnv := &stringWithAlternative{value: defaultValue, alternative: envSubstitution}
+		staticWithEnv := &valueWithAlternative{value: defaultValue, alternative: envSubstitution}
 		object := Object{"a": staticWithEnv}
 		err := resolveSubstitutions(object)
 
@@ -696,36 +709,58 @@ func TestResolveSubstitutions(t *testing.T) {
 		assertError(t, err, expectedError)
 	})
 
-	t.Run("extract string with alternative value", func(t *testing.T) {
-		parser := newParser(strings.NewReader("a: static, a:${?b}"))
-		expected := Object{"a": &stringWithAlternative{
-			value: "static",
-			alternative: &Substitution{
-				path:     "b",
-				optional: true,
-			},
+	t.Run("extract valueWithAlternative value with string type", func(t *testing.T) {
+		parser := newParser(strings.NewReader("a: stringValue, a:${?b}"))
+		expected := Object{"a": &valueWithAlternative{
+			value:       String("stringValue"),
+			alternative: &Substitution{path: "b", optional: true},
 		}}
 		got, err := parser.extractObject()
 		assertNoError(t, err)
-		if !reflect.DeepEqual(expected, got) {
-			t.Errorf("expected: %v, got: %v", expected, got)
-		}
+		assertDeepEqual(t, got, expected)
 	})
 
-	t.Run("extract string with alternative value and overwrite alternatives", func(t *testing.T) {
-		parser := newParser(strings.NewReader("a: static, a:${?c}, a:${?b}"))
-		expected := Object{"a": &stringWithAlternative{
-			value: "static",
-			alternative: &Substitution{
-				path:     "b",
-				optional: true,
-			},
+	t.Run("extract valueWithAlternative value with number type", func(t *testing.T) {
+		parser := newParser(strings.NewReader("a: 1, a:${?b}"))
+		expected := Object{"a": &valueWithAlternative{
+			value:       Int(1),
+			alternative: &Substitution{path: "b", optional: true},
+		}}
+		got, err := parser.extractObject()
+		assertNoError(t, err)
+		assertDeepEqual(t, got, expected)
+	})
+
+	t.Run("extract valueWithAlternative value with duration type", func(t *testing.T) {
+		parser := newParser(strings.NewReader("a: 1s, a:${?b}"))
+		expected := Object{"a": &valueWithAlternative{
+			value:       Duration(time.Second),
+			alternative: &Substitution{path: "b", optional: true},
+		}}
+		got, err := parser.extractObject()
+		assertNoError(t, err)
+		assertDeepEqual(t, got, expected)
+	})
+
+	t.Run("extract valueWithAlternative value with boolean type", func(t *testing.T) {
+		parser := newParser(strings.NewReader("a: true, a:${?b}"))
+		expected := Object{"a": &valueWithAlternative{
+			value:       Boolean(true),
+			alternative: &Substitution{path: "b", optional: true},
 		}}
 		got, err := parser.extractObject()
 		assertNoError(t, err)
-		if !reflect.DeepEqual(expected, got) {
-			t.Errorf("expected: %v, got: %v", expected, got)
+		assertDeepEqual(t, got, expected)
+	})
+
+	t.Run("extract valueWithAlternative value and overwrite alternatives", func(t *testing.T) {
+		parser := newParser(strings.NewReader("a: static, a:${?b}"))
+		expected := Object{
+			"a": &valueWithAlternative{value: String("static"), alternative: &Substitution{path: "b", optional: true}},
 		}
+		got, err := parser.extractObject()
+		assertNoError(t, err)
+		assertDeepEqual(t, got, expected)
 	})
 }