diff --git a/internal/command/apply_test.go b/internal/command/apply_test.go
index 89449163a722..14bac07a54f0 100644
--- a/internal/command/apply_test.go
+++ b/internal/command/apply_test.go
@@ -964,16 +964,10 @@ func TestApply_planWithVarFileChangingVariableValue(t *testing.T) {
 	}
 }
 
-func TestApply_planVars(t *testing.T) {
-	// This test ensures that it isn't allowed to set non-ephemeral input
-	// variables when applying from a saved plan file, since in that case the
-	// variable values come from the saved plan file.
-	//
-	// This situation was originally checked by the apply command itself,
-	// and that's what this test was originally exercising. This rule
-	// is now enforced by the "local" backend instead, but this test
-	// is still valid since the command instance delegates to the
-	// local backend.
+func TestApply_planUndeclaredVars(t *testing.T) {
+	// This test ensures that it isn't allowed to set undeclared input variables
+	// when applying from a saved plan file, since in that case the variable
+	// values come from the saved plan file.
 
 	planPath := applyFixturePlanFile(t)
 	statePath := testTempFile(t)
@@ -1076,7 +1070,6 @@ foo = "bar"
 
 		"with planfile passing ephemeral variable through environment variable": func(t *testing.T, c *ApplyCommand, statePath, planPath string, done func(*testing.T) *terminal.TestOutput) {
 			t.Setenv("TF_VAR_foo", "bar")
-			defer t.Setenv("TF_VAR_foo", "")
 
 			args := []string{
 				"-state", statePath,
@@ -1168,7 +1161,7 @@ foo = "bar"
 
 		"without planfile passing ephemeral variable through environment variable": func(t *testing.T, c *ApplyCommand, statePath, planPath string, done func(*testing.T) *terminal.TestOutput) {
 			t.Setenv("TF_VAR_foo", "bar")
-			defer t.Setenv("TF_VAR_foo", "")
+			t.Setenv("TF_VAR_unused", `{key:"val"}`)
 
 			args := []string{
 				"-state", statePath,
diff --git a/internal/command/testdata/apply-ephemeral-variable/main.tf b/internal/command/testdata/apply-ephemeral-variable/main.tf
index f1b83b2052e3..7961a3b9a1ab 100644
--- a/internal/command/testdata/apply-ephemeral-variable/main.tf
+++ b/internal/command/testdata/apply-ephemeral-variable/main.tf
@@ -9,6 +9,11 @@ variable "bar" {
   ephemeral = true
 }
 
+variable "unused" {
+  type = map(string)
+  default = null
+}
+
 resource "test_instance" "foo" {
   ami = "bar"
 }