diff --git a/internal/omap/orderedmap.go b/internal/omap/orderedmap.go
index cf7fc22c7f..4d2719dfdc 100644
--- a/internal/omap/orderedmap.go
+++ b/internal/omap/orderedmap.go
@@ -4,6 +4,7 @@ import (
 	"cmp"
 	"fmt"
 	"slices"
+	"sync"
 
 	"gopkg.in/yaml.v3"
 
@@ -15,49 +16,56 @@ import (
 // list of the map's keys. This allows you to run deterministic and ordered
 // operations on the map such as printing/serializing/iterating.
 type OrderedMap[K cmp.Ordered, V any] struct {
-	s []K
-	m map[K]V
+	mutex sync.RWMutex
+	s     []K
+	m     map[K]V
 }
 
 // New will create a new OrderedMap of the given type and return it.
 func New[K cmp.Ordered, V any]() OrderedMap[K, V] {
-	return OrderedMap[K, V]{
-		s: make([]K, 0),
-		m: make(map[K]V),
-	}
+	return OrderedMap[K, V]{}
 }
 
 // FromMap will create a new OrderedMap from the given map. Since Golang maps
 // are unordered, the order of the created OrderedMap will be random.
 func FromMap[K cmp.Ordered, V any](m map[K]V) OrderedMap[K, V] {
-	om := New[K, V]()
-	om.m = m
-	om.s = exp.Keys(m)
-	return om
+	mm := deepcopy.Map(m)
+	ms := exp.Keys(mm)
+	return OrderedMap[K, V]{
+		m: mm,
+		s: ms,
+	}
 }
 
 func FromMapWithOrder[K cmp.Ordered, V any](m map[K]V, order []K) OrderedMap[K, V] {
-	om := New[K, V]()
 	if len(m) != len(order) {
 		panic("length of map and order must be equal")
 	}
-	om.m = m
-	om.s = order
-	for key := range om.m {
-		if !slices.Contains(om.s, key) {
+
+	for key := range m {
+		if !slices.Contains(order, key) {
 			panic("order keys must match map keys")
 		}
 	}
-	return om
+
+	return OrderedMap[K, V]{
+		s: slices.Clone(order),
+		m: deepcopy.Map(m),
+	}
 }
 
 // Len will return the number of items in the map.
-func (om *OrderedMap[K, V]) Len() int {
-	return len(om.s)
+func (om *OrderedMap[K, V]) Len() (l int) {
+	om.mutex.RLock()
+	l = len(om.s)
+	om.mutex.RUnlock()
+
+	return
 }
 
 // Set will set the value for a given key.
 func (om *OrderedMap[K, V]) Set(key K, value V) {
+	om.mutex.Lock()
 	if om.m == nil {
 		om.m = make(map[K]V)
 	}
@@ -65,11 +73,19 @@ func (om *OrderedMap[K, V]) Set(key K, value V) {
 		om.s = append(om.s, key)
 	}
 	om.m[key] = value
+	om.mutex.Unlock()
 }
 
 // Get will return the value for a given key.
 // If the key does not exist, it will return the zero value of the value type.
 func (om *OrderedMap[K, V]) Get(key K) V {
+	om.mutex.RLock()
+	defer om.mutex.RUnlock()
+
+	if om.m == nil {
+		var zero V
+		return zero
+	}
 	value, ok := om.m[key]
 	if !ok {
 		var zero V
@@ -80,38 +96,52 @@ func (om *OrderedMap[K, V]) Get(key K) V {
 
 // Exists will return whether or not the given key exists.
 func (om *OrderedMap[K, V]) Exists(key K) bool {
+	om.mutex.RLock()
 	_, ok := om.m[key]
+	om.mutex.RUnlock()
 	return ok
 }
 
 // Sort will sort the map.
 func (om *OrderedMap[K, V]) Sort() {
+	om.mutex.Lock()
 	slices.Sort(om.s)
+	om.mutex.Unlock()
 }
 
 // SortFunc will sort the map using the given function.
 func (om *OrderedMap[K, V]) SortFunc(less func(i, j K) int) {
+	om.mutex.Lock()
 	slices.SortFunc(om.s, less)
+	om.mutex.Unlock()
 }
 
 // Keys will return a slice of the map's keys in order.
 func (om *OrderedMap[K, V]) Keys() []K {
-	return om.s
+	om.mutex.RLock()
+	keys := deepcopy.Slice(om.s)
+	om.mutex.RUnlock()
+
+	return keys
 }
 
 // Values will return a slice of the map's values in order.
 func (om *OrderedMap[K, V]) Values() []V {
-	var values []V
+	om.mutex.RLock()
+	values := make([]V, 0, len(om.m))
 	for _, key := range om.s {
 		values = append(values, om.m[key])
 	}
+	om.mutex.RUnlock()
+
 	return values
 }
 
 // Range will iterate over the map and call the given function for each key/value.
 func (om *OrderedMap[K, V]) Range(fn func(key K, value V) error) error {
-	for _, key := range om.s {
-		if err := fn(key, om.m[key]); err != nil {
+	keys := om.Keys()
+	for _, key := range keys {
+		if err := fn(key, om.Get(key)); err != nil {
 			return err
 		}
 	}
@@ -119,22 +149,33 @@ func (om *OrderedMap[K, V]) Range(fn func(key K, value V) error) error {
 }
 
 // Merge merges the given Vars into the caller one
-func (om *OrderedMap[K, V]) Merge(other OrderedMap[K, V]) {
-	// nolint: errcheck
-	other.Range(func(key K, value V) error {
+func (om *OrderedMap[K, V]) Merge(other *OrderedMap[K, V]) {
+	_ = other.Range(func(key K, value V) error {
 		om.Set(key, value)
 		return nil
 	})
 }
 
 func (om *OrderedMap[K, V]) DeepCopy() OrderedMap[K, V] {
+	om.mutex.RLock()
+	s := deepcopy.Slice(om.s)
+	m := deepcopy.Map(om.m)
+	om.mutex.RUnlock()
+
 	return OrderedMap[K, V]{
-		s: deepcopy.Slice(om.s),
-		m: deepcopy.Map(om.m),
+		s: s,
+		m: m,
 	}
 }
 
 func (om *OrderedMap[K, V]) UnmarshalYAML(node *yaml.Node) error {
+	if om == nil {
+		*om = OrderedMap[K, V]{
+			m: make(map[K]V),
+			s: make([]K, 0),
+		}
+	}
+
 	switch node.Kind {
 	// Even numbers contain the keys
 	// Odd numbers contain the values
@@ -158,7 +199,7 @@ func (om *OrderedMap[K, V]) UnmarshalYAML(node *yaml.Node) error {
 			om.Set(k, v)
 		}
 		return nil
+	default:
+		return fmt.Errorf("yaml: line %d: cannot unmarshal %s into variables", node.Line, node.ShortTag())
 	}
-
-	return fmt.Errorf("yaml: line %d: cannot unmarshal %s into variables", node.Line, node.ShortTag())
 }
diff --git a/internal/omap/orderedmap_test.go b/internal/omap/orderedmap_test.go
index c1adc9b311..6523184bbb 100644
--- a/internal/omap/orderedmap_test.go
+++ b/internal/omap/orderedmap_test.go
@@ -89,7 +89,7 @@ func TestOrderedMapMerge(t *testing.T) {
 	om2.Set("b", 3)
 	om2.Set("c", 4)
 
-	om1.Merge(om2)
+	om1.Merge(&om2)
 
 	expectedKeys := []string{"a", "b", "c"}
 	expectedValues := []int{1, 3, 4}
diff --git a/internal/summary/summary_test.go b/internal/summary/summary_test.go
index a478b1a2fb..6a14630cf2 100644
--- a/internal/summary/summary_test.go
+++ b/internal/summary/summary_test.go
@@ -156,13 +156,13 @@ func TestPrintAllWithSpaces(t *testing.T) {
 	t2 := &ast.Task{Task: "t2"}
 	t3 := &ast.Task{Task: "t3"}
 
-	tasks := ast.Tasks{}
-	tasks.Set("t1", t1)
-	tasks.Set("t2", t2)
-	tasks.Set("t3", t3)
+	var tf ast.Taskfile
+	tf.Tasks.Set("t1", t1)
+	tf.Tasks.Set("t2", t2)
+	tf.Tasks.Set("t3", t3)
 
 	summary.PrintTasks(&l,
-		&ast.Taskfile{Tasks: tasks},
+		&tf,
 		[]*ast.Call{{Task: "t1"}, {Task: "t2"}, {Task: "t3"}})
 
 	assert.True(t, strings.HasPrefix(buffer.String(), "task: t1"))
diff --git a/taskfile/ast/for.go b/taskfile/ast/for.go
index 35d7ce7f60..3f0e8900c6 100644
--- a/taskfile/ast/for.go
+++ b/taskfile/ast/for.go
@@ -52,7 +52,7 @@ func (f *For) UnmarshalYAML(node *yaml.Node) error {
 		if forStruct.Var != "" && forStruct.Matrix.Len() != 0 {
 			return errors.NewTaskfileDecodeError(nil, node).WithMessage("cannot use both var and matrix in for")
 		}
-		f.Matrix = forStruct.Matrix
+		f.Matrix = forStruct.Matrix.DeepCopy()
 		f.Var = forStruct.Var
 		f.Split = forStruct.Split
 		f.As = forStruct.As
diff --git a/taskfile/ast/taskfile.go b/taskfile/ast/taskfile.go
index 9e0c0b7924..d9169093fb 100644
--- a/taskfile/ast/taskfile.go
+++ b/taskfile/ast/taskfile.go
@@ -55,7 +55,8 @@ func (t1 *Taskfile) Merge(t2 *Taskfile, include *Include) error {
 	}
 	t1.Vars.Merge(t2.Vars, include)
 	t1.Env.Merge(t2.Env, include)
-	return t1.Tasks.Merge(t2.Tasks, include, t1.Vars)
+
+	return t1.Tasks.Merge(&t2.Tasks, include, t1.Vars)
 }
 
 func (tf *Taskfile) UnmarshalYAML(node *yaml.Node) error {
@@ -87,7 +88,7 @@ func (tf *Taskfile) UnmarshalYAML(node *yaml.Node) error {
 		tf.Shopt = taskfile.Shopt
 		tf.Vars = taskfile.Vars
 		tf.Env = taskfile.Env
-		tf.Tasks = taskfile.Tasks
+		tf.Tasks = taskfile.Tasks.DeepCopy()
 		tf.Silent = taskfile.Silent
 		tf.Dotenv = taskfile.Dotenv
 		tf.Run = taskfile.Run
diff --git a/taskfile/ast/tasks.go b/taskfile/ast/tasks.go
index cfe29a8da3..a663112550 100644
--- a/taskfile/ast/tasks.go
+++ b/taskfile/ast/tasks.go
@@ -17,6 +17,12 @@ type Tasks struct {
 	omap.OrderedMap[string, *Task]
 }
 
+func (t *Tasks) DeepCopy() Tasks {
+	return Tasks{
+		OrderedMap: t.OrderedMap.DeepCopy(),
+	}
+}
+
 type MatchingTask struct {
 	Task      *Task
 	Wildcards []string
@@ -47,7 +53,7 @@ func (t *Tasks) FindMatchingTasks(call *Call) []*MatchingTask {
 	return matchingTasks
 }
 
-func (t1 *Tasks) Merge(t2 Tasks, include *Include, includedTaskfileVars *Vars) error {
+func (t1 *Tasks) Merge(t2 *Tasks, include *Include, includedTaskfileVars *Vars) error {
 	err := t2.Range(func(name string, v *Task) error {
 		// We do a deep copy of the task struct here to ensure that no data can
 		// be changed elsewhere once the taskfile is merged.
@@ -152,13 +158,10 @@ func (t *Tasks) UnmarshalYAML(node *yaml.Node) error {
 					}
 				}
 			}
-			tasks.Set(name, task)
+			t.Set(name, task)
 			return nil
 		})
 
-		*t = Tasks{
-			OrderedMap: tasks,
-		}
 		return nil
 	}
 
diff --git a/variables.go b/variables.go
index cfdb70ae46..d6a8613073 100644
--- a/variables.go
+++ b/variables.go
@@ -274,7 +274,7 @@ func itemsFromFor(
 	var values []any  // The list of values to loop over
 	// Get the list from a matrix
 	if f.Matrix.Len() != 0 {
-		return asAnySlice(product(f.Matrix)), nil, nil
+		return asAnySlice(product(&f.Matrix)), nil, nil
 	}
 	// Get the list from the explicit for list
 	if len(f.List) > 0 {
@@ -329,7 +329,7 @@ func itemsFromFor(
 }
 
 // product generates the cartesian product of the input map of slices.
-func product(inputMap omap.OrderedMap[string, []any]) []map[string]any {
+func product(inputMap *omap.OrderedMap[string, []any]) []map[string]any {
 	if inputMap.Len() == 0 {
 		return nil
 	}