diff --git a/env.go b/env.go
index 6841404a..dd1859c4 100644
--- a/env.go
+++ b/env.go
@@ -5,8 +5,8 @@ import "context"
 type env struct {
 	pc        int
 	stack     *stack
-	scopes    *stack
 	paths     *stack
+	scopes    *scopeStack
 	values    []interface{}
 	codes     []*code
 	codeinfos []codeinfo
@@ -22,8 +22,8 @@ type env struct {
 func newEnv(ctx context.Context) *env {
 	return &env{
 		stack:  newStack(),
-		scopes: newStack(),
 		paths:  newStack(),
+		scopes: newScopeStack(),
 		ctx:    ctx,
 	}
 }
diff --git a/execute.go b/execute.go
index 2e1e0869..e9509574 100644
--- a/execute.go
+++ b/execute.go
@@ -212,7 +212,7 @@ loop:
 				env.scopes.index = index
 			}
 			if outerindex = index; outerindex >= 0 {
-				if s := env.scopes.data[outerindex].value.(scope); s.id == xs[0] {
+				if s := env.scopes.data[outerindex].value; s.id == xs[0] {
 					outerindex = s.outerindex
 				}
 			}
@@ -349,7 +349,7 @@ func (env *env) pop() interface{} {
 
 func (env *env) popscope() (int, int) {
 	free := env.scopes.index > env.scopes.limit
-	s := env.scopes.pop().(scope)
+	s := env.scopes.pop()
 	if free {
 		env.offset = s.offset
 	}
@@ -377,7 +377,7 @@ func (env *env) popfork() int {
 
 func (env *env) index(v [2]int) int {
 	for id, i := v[0], env.scopes.index; i >= 0; {
-		s := env.scopes.data[i].value.(scope)
+		s := env.scopes.data[i].value
 		if s.id == id {
 			return s.offset + v[1]
 		}
diff --git a/scope_stack.go b/scope_stack.go
new file mode 100644
index 00000000..82d620be
--- /dev/null
+++ b/scope_stack.go
@@ -0,0 +1,51 @@
+package gojq
+
+type scopeStack struct {
+	data  []scopeBlock
+	index int
+	limit int
+}
+
+type scopeBlock struct {
+	value scope
+	next  int
+}
+
+func newScopeStack() *scopeStack {
+	return &scopeStack{index: -1, limit: -1}
+}
+
+func (s *scopeStack) push(v scope) {
+	b := scopeBlock{v, s.index}
+	i := s.index + 1
+	if i <= s.limit {
+		i = s.limit + 1
+	}
+	s.index = i
+	if i < len(s.data) {
+		s.data[i] = b
+	} else {
+		s.data = append(s.data, b)
+	}
+}
+
+func (s *scopeStack) pop() scope {
+	b := s.data[s.index]
+	s.index = b.next
+	return b.value
+}
+
+func (s *scopeStack) empty() bool {
+	return s.index < 0
+}
+
+func (s *scopeStack) save(index, limit *int) {
+	*index, *limit = s.index, s.limit
+	if s.index > s.limit {
+		s.limit = s.index
+	}
+}
+
+func (s *scopeStack) restore(index, limit int) {
+	s.index, s.limit = index, limit
+}