diff --git a/platform/core-api/src/com/intellij/openapi/project/ProjectCoreUtil.java b/platform/core-api/src/com/intellij/openapi/project/ProjectCoreUtil.java
index 8efb95e3e1cb..b803be552766 100644
--- a/platform/core-api/src/com/intellij/openapi/project/ProjectCoreUtil.java
+++ b/platform/core-api/src/com/intellij/openapi/project/ProjectCoreUtil.java
@@ -27,7 +27,7 @@ import org.jetbrains.annotations.Nullable;
 
 public class ProjectCoreUtil {
   @Deprecated
-  @ApiStatus.Experimental
+  @ApiStatus.Internal
   public static volatile Project theProject;
 
   public static boolean isProjectOrWorkspaceFile(@NotNull VirtualFile file) {
@@ -41,8 +41,12 @@ public class ProjectCoreUtil {
   }
 
   /**
+   * For internal usage only.
+   * Please use {@link com.intellij.psi.PsiElement#getProject()} or {@link com.intellij.openapi.project.ProjectManager#getOpenProjects()} instead.
    * @return the only open project if there is one, null if no projects open, or several projects are open, or default project is created
    */
+  @Deprecated
+  @ApiStatus.Internal
   @Nullable
   public static Project theOnlyOpenProject() {
     return theProject;
diff --git a/platform/core-impl/src/com/intellij/openapi/application/ex/ApplicationEx.java b/platform/core-impl/src/com/intellij/openapi/application/ex/ApplicationEx.java
index 284ba1f94ccc..ad3501d46bdd 100644
--- a/platform/core-impl/src/com/intellij/openapi/application/ex/ApplicationEx.java
+++ b/platform/core-impl/src/com/intellij/openapi/application/ex/ApplicationEx.java
@@ -133,12 +133,14 @@ public interface ApplicationEx extends Application {
 
   /** DO NOT USE */
   @Deprecated
+  @ApiStatus.Internal
   default void executeByImpatientReader(@NotNull Runnable runnable) throws ApplicationUtil.CannotRunReadActionException {
     runnable.run();
   }
 
   /** DO NOT USE */
   @Deprecated
+  @ApiStatus.Internal
   default boolean isInImpatientReader() {
     return false;
   }