diff --git a/dexpreopt/class_loader_context.go b/dexpreopt/class_loader_context.go
index 8d6190190..2b6ec79bb 100644
--- a/dexpreopt/class_loader_context.go
+++ b/dexpreopt/class_loader_context.go
@@ -110,6 +110,13 @@ func (clcMap ClassLoaderContextMap) addContext(ctx android.ModuleInstallPathCont
 		devicePath = android.InstallPathToOnDevicePath(ctx, installPath.(android.InstallPath))
 	}
 
+	// Nested class loader context shouldn't have conditional part (it is allowed only at the top level).
+	for ver, _ := range nestedClcMap {
+		if ver != AnySdkVersion {
+			clcStr, _ := ComputeClassLoaderContext(nestedClcMap)
+			return fmt.Errorf("nested class loader context shouldn't have conditional part: %s", clcStr)
+		}
+	}
 	subcontexts := nestedClcMap[AnySdkVersion]
 
 	// If the library with this name is already present as one of the unconditional top-level
diff --git a/dexpreopt/class_loader_context_test.go b/dexpreopt/class_loader_context_test.go
index 269a0dbc0..aed354367 100644
--- a/dexpreopt/class_loader_context_test.go
+++ b/dexpreopt/class_loader_context_test.go
@@ -194,6 +194,16 @@ func TestCLCMaybeAdd(t *testing.T) {
 	})
 }
 
+// An attempt to add conditional nested subcontext should fail.
+func TestCLCNestedConditional(t *testing.T) {
+	ctx := testContext()
+	m1 := make(ClassLoaderContextMap)
+	m1.AddContextForSdk(ctx, 42, "a", buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+	m := make(ClassLoaderContextMap)
+	err := m.addContext(ctx, AnySdkVersion, "b", buildPath(ctx, "b"), installPath(ctx, "b"), true, m1)
+	checkError(t, err, "nested class loader context shouldn't have conditional part")
+}
+
 func checkError(t *testing.T, have error, want string) {
 	if have == nil {
 		t.Errorf("\nwant error: '%s'\nhave: none", want)