diff --git a/eo-runtime/src/main/java/org/eolang/Data.java b/eo-runtime/src/main/java/org/eolang/Data.java
index 7e167baf8a..21c5719429 100644
--- a/eo-runtime/src/main/java/org/eolang/Data.java
+++ b/eo-runtime/src/main/java/org/eolang/Data.java
@@ -48,86 +48,6 @@ public interface Data<T> {
      */
     T take();
 
-    /**
-     * Data being returned only once, from encapsulated object.
-     *
-     * @param <T> The type of data
-     * @since 0.1
-     */
-    final class Once<T> implements Data<T> {
-
-        /**
-         * Data.
-         */
-        private final Data<T> src;
-
-        /**
-         * Reference.
-         */
-        private final AtomicReference<T> ref;
-
-        /**
-         * Blank supplier.
-         */
-        private final Supplier<String> blank;
-
-        /**
-         * Ctor.
-         * @param data Data to return
-         * @param txt Missing data text
-         */
-        public Once(final Data<T> data, final Supplier<String> txt) {
-            this.src = data;
-            this.ref = new AtomicReference<>();
-            this.blank = txt;
-        }
-
-        @Override
-        public int hashCode() {
-            return this.take().hashCode();
-        }
-
-        @Override
-        public boolean equals(final Object obj) {
-            if (this == obj) {
-                return true;
-            }
-            if (obj == null || getClass() != obj.getClass()) {
-                return false;
-            }
-            return this.take().equals(((Once<?>) obj).take());
-        }
-
-        @Override
-        public String toString() {
-            final T data = this.ref.get();
-            String txt = this.blank.get();
-            if (txt.isEmpty()) {
-                txt = this.take().toString();
-            } else if (data != null) {
-                txt = data.toString();
-            }
-            return txt;
-        }
-
-        @Override
-        public T take() {
-            synchronized (this.ref) {
-                return this.ref.updateAndGet(
-                    t -> {
-                        final T result;
-                        if (t == null) {
-                            result = Once.this.src.take();
-                        } else {
-                            result = t;
-                        }
-                        return result;
-                    }
-                );
-            }
-        }
-    }
-
     /**
      * Makes a {@link Phi} out of a Java object, like {@link String} or {@link Integer}.
      *
diff --git a/eo-runtime/src/main/java/org/eolang/PhOnce.java b/eo-runtime/src/main/java/org/eolang/PhOnce.java
index 76f3923718..235c94921f 100644
--- a/eo-runtime/src/main/java/org/eolang/PhOnce.java
+++ b/eo-runtime/src/main/java/org/eolang/PhOnce.java
@@ -24,6 +24,7 @@
 
 package org.eolang;
 
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Supplier;
 
 /**
@@ -37,82 +38,105 @@ class PhOnce implements Phi {
     /**
      * The object fetched.
      */
-    private final Data<Phi> object;
+    private final Supplier<Phi> object;
 
     /**
-     * The expression provider.
+     * As string representation.
      */
-    private final Supplier<String> exp;
+    private final Supplier<String> string;
+
+    /**
+     * As φ term representation.
+     */
+    private final Supplier<String> term;
+
+    /**
+     * Reference.
+     */
+    private final AtomicReference<Phi> ref;
 
     /**
      * Ctor.
      *
-     * @param data The object
-     * @param blank The string value
-     * @param expr The expression
+     * @param obj The object
+     * @param str The "as string" value
+     * @param trm The "as φ term" value
      */
-    PhOnce(final Data<Phi> data, final Supplier<String> blank, final Supplier<String> expr) {
-        this.object = new Data.Once<>(data, blank);
-        this.exp = expr;
+    PhOnce(final Supplier<Phi> obj, final Supplier<String> str, final Supplier<String> trm) {
+        this.ref = new AtomicReference<>(null);
+        this.object = () -> {
+            synchronized (this.ref) {
+                if (this.ref.get() == null) {
+                    this.ref.set(obj.get());
+                }
+                return this.ref.get();
+            }
+        };
+        this.string = str;
+        this.term = trm;
     }
 
     @Override
     public boolean equals(final Object obj) {
-        return this.object.take().equals(obj);
+        return this.object.get().equals(obj);
     }
 
     @Override
     public int hashCode() {
-        return this.object.take().hashCode();
+        return this.object.get().hashCode();
     }
 
     @Override
     public final String toString() {
-        return this.object.toString();
+        return this.string.get();
     }
 
     @Override
     public final String φTerm() {
-        return this.exp.get();
+        return this.term.get();
     }
 
     @Override
     public Phi copy() {
-        return this.object.take().copy();
+        return new PhOnce(
+            () -> this.object.get().copy(),
+            () -> String.format("%s'", this.string),
+            this.term
+        );
     }
 
     @Override
     public Phi take(final int pos) {
-        return this.object.take().take(pos);
+        return this.object.get().take(pos);
     }
 
     @Override
     public Phi take(final String name) {
-        return this.object.take().take(name);
+        return this.object.get().take(name);
     }
 
     @Override
     public Phi take(final String name, final Phi rho) {
-        return this.object.take().take(name, rho);
+        return this.object.get().take(name, rho);
     }
 
     @Override
     public void put(final int pos, final Phi obj) {
-        this.object.take().put(pos, obj);
+        this.object.get().put(pos, obj);
     }
 
     @Override
     public void put(final String name, final Phi obj) {
-        this.object.take().put(name, obj);
+        this.object.get().put(name, obj);
     }
 
     @Override
     public String locator() {
-        return this.object.take().locator();
+        return this.object.get().locator();
     }
 
     @Override
     public String forma() {
-        return this.object.take().forma();
+        return this.object.get().forma();
     }
 }
diff --git a/eo-runtime/src/test/eo/org/eolang/switch-tests.eo b/eo-runtime/src/test/eo/org/eolang/switch-tests.eo
index 15094a1f9f..8036571bbf 100644
--- a/eo-runtime/src/test/eo/org/eolang/switch-tests.eo
+++ b/eo-runtime/src/test/eo/org/eolang/switch-tests.eo
@@ -27,9 +27,6 @@
 +version 0.0.0
 
 # Test.
-# @todo #2931:30min Enable the test switch-with-all-false-cases. For some reason it fails with
-#  "Given index is out of tuple bounds". It seems comparison inside "switch" does not work properly
-#  Need to find out what's going on and enable the test.
 [] > switch-simple-case
   eq. > @
     switch
@@ -77,17 +74,14 @@
 
 # Test.
 [] > switch-with-all-false-cases
-  eq. > res
-    switch
+  switch > @
+    *
       *
-        *
-          FALSE
-          "FALSE1"
-        *
-          FALSE
-          "FALSE2"
-    TRUE
-  TRUE > @
+        FALSE
+        "FALSE1"
+      *
+        FALSE
+        "FALSE2"
 
 # Test.
 [] > switch-case-with-error