diff --git a/android/guava-testlib/src/com/google/common/testing/EqualsTester.java b/android/guava-testlib/src/com/google/common/testing/EqualsTester.java
index dc2d1972c95e..2c8e08b87c57 100644
--- a/android/guava-testlib/src/com/google/common/testing/EqualsTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/EqualsTester.java
@@ -127,6 +127,11 @@ private void testItems() {
           "the Object#hashCode of " + item + " must be consistent",
           item.hashCode(),
           item.hashCode());
+      if (!(item instanceof String)) {
+        assertTrue(
+            item + " must not be Object#equals to its Object#toString representation",
+            !item.equals(item.toString()));
+      }
     }
   }
 
diff --git a/android/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java b/android/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java
index b992f1b4bf1f..d615af6633a2 100644
--- a/android/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java
+++ b/android/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java
@@ -272,6 +272,15 @@ public void testEqualityGroups() {
         .testEquals();
   }
 
+  public void testEqualityBasedOnToString() {
+    try {
+      new EqualsTester().addEqualityGroup(new EqualsBasedOnToString("foo")).testEquals();
+      fail();
+    } catch (AssertionFailedError e) {
+      assertTrue(e.getMessage().contains("toString representation"));
+    }
+  }
+
   private static void assertErrorMessage(Throwable e, String message) {
     // TODO(kevinb): use a Truth assertion here
     if (!e.getMessage().contains(message)) {
@@ -422,4 +431,27 @@ public String toString() {
       return name;
     }
   }
+
+  private static final class EqualsBasedOnToString {
+    private final String s;
+
+    private EqualsBasedOnToString(String s) {
+      this.s = s;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      return obj != null && obj.toString().equals(toString());
+    }
+
+    @Override
+    public int hashCode() {
+      return s.hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return s;
+    }
+  }
 }
diff --git a/guava-gwt/test/com/google/common/testing/EqualsTesterTest_gwt.java b/guava-gwt/test/com/google/common/testing/EqualsTesterTest_gwt.java
index 1c1fade62f88..acf3aa534111 100644
--- a/guava-gwt/test/com/google/common/testing/EqualsTesterTest_gwt.java
+++ b/guava-gwt/test/com/google/common/testing/EqualsTesterTest_gwt.java
@@ -42,6 +42,12 @@ public void testAddTwoEqualObjectsAtOnceWithNull() throws Exception {
   testCase.testAddTwoEqualObjectsAtOnceWithNull();
 }
 
+public void testEqualityBasedOnToString() throws Exception {
+  com.google.common.testing.EqualsTesterTest testCase = new com.google.common.testing.EqualsTesterTest();
+  testCase.setUp();
+  testCase.testEqualityBasedOnToString();
+}
+
 public void testEqualityGroups() throws Exception {
   com.google.common.testing.EqualsTesterTest testCase = new com.google.common.testing.EqualsTesterTest();
   testCase.setUp();
diff --git a/guava-testlib/src/com/google/common/testing/EqualsTester.java b/guava-testlib/src/com/google/common/testing/EqualsTester.java
index dc2d1972c95e..2c8e08b87c57 100644
--- a/guava-testlib/src/com/google/common/testing/EqualsTester.java
+++ b/guava-testlib/src/com/google/common/testing/EqualsTester.java
@@ -127,6 +127,11 @@ private void testItems() {
           "the Object#hashCode of " + item + " must be consistent",
           item.hashCode(),
           item.hashCode());
+      if (!(item instanceof String)) {
+        assertTrue(
+            item + " must not be Object#equals to its Object#toString representation",
+            !item.equals(item.toString()));
+      }
     }
   }
 
diff --git a/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java b/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java
index b992f1b4bf1f..d615af6633a2 100644
--- a/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java
+++ b/guava-testlib/test/com/google/common/testing/EqualsTesterTest.java
@@ -272,6 +272,15 @@ public void testEqualityGroups() {
         .testEquals();
   }
 
+  public void testEqualityBasedOnToString() {
+    try {
+      new EqualsTester().addEqualityGroup(new EqualsBasedOnToString("foo")).testEquals();
+      fail();
+    } catch (AssertionFailedError e) {
+      assertTrue(e.getMessage().contains("toString representation"));
+    }
+  }
+
   private static void assertErrorMessage(Throwable e, String message) {
     // TODO(kevinb): use a Truth assertion here
     if (!e.getMessage().contains(message)) {
@@ -422,4 +431,27 @@ public String toString() {
       return name;
     }
   }
+
+  private static final class EqualsBasedOnToString {
+    private final String s;
+
+    private EqualsBasedOnToString(String s) {
+      this.s = s;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      return obj != null && obj.toString().equals(toString());
+    }
+
+    @Override
+    public int hashCode() {
+      return s.hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return s;
+    }
+  }
 }