diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index e958b105b24c7cd182c09a2408e04fff86cefe78..87558e6d0eccde22cc8cd625a619bccb1984d2a4 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -552,9 +552,11 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				return extHostQuickOpen.createInputBox(extension.identifier);
 			},
 			get activeColorTheme(): vscode.ColorTheme {
+				checkProposedApiEnabled(extension);
 				return extHostTheming.activeColorTheme;
 			},
 			onDidChangeActiveColorTheme(listener, thisArg?, disposables?) {
+				checkProposedApiEnabled(extension);
 				return extHostTheming.onDidChangeActiveColorTheme(listener, thisArg, disposables);
 			}
 		};