diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableBooleanTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableBooleanTest.java
index 09c793c58..c7634d80d 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableBooleanTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableBooleanTest.java
@@ -17,11 +17,12 @@
 
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * JUnit tests.
@@ -42,10 +43,10 @@ public void testCompareTo() {
         assertEquals(0, mutBool.compareTo(new MutableBoolean(true)));
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testCompareToNull() {
         final MutableBoolean mutBool = new MutableBoolean(false);
-        mutBool.compareTo(null);
+        assertThrows(NullPointerException.class, () -> mutBool.compareTo(null));
     }
 
     // ----------------------------------------------------------------
@@ -61,9 +62,9 @@ public void testConstructors() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testConstructorNull() {
-        new MutableBoolean(null);
+        assertThrows(NullPointerException.class, () -> new MutableBoolean(null));
     }
 
     @Test
@@ -115,10 +116,10 @@ public void testGetSet() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testSetNull() {
         final MutableBoolean mutBool = new MutableBoolean(false);
-        mutBool.setValue(null);
+        assertThrows(NullPointerException.class, () -> mutBool.setValue(null));
     }
 
     @Test
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableByteTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableByteTest.java
index 61dfd0d9c..91ad38cfa 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableByteTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableByteTest.java
@@ -16,11 +16,12 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * JUnit tests.
@@ -43,9 +44,9 @@ public void testConstructors() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testConstructorNull() {
-        new MutableByte((Number)null);
+        assertThrows(NullPointerException.class, () -> new MutableByte((Number)null));
     }
 
     @Test
@@ -67,10 +68,10 @@ public void testGetSet() {
         assertEquals(Byte.valueOf((byte) 3), mutNum.getValue());
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testSetNull() {
         final MutableByte mutNum = new MutableByte((byte) 0);
-        mutNum.setValue(null);
+        assertThrows(NullPointerException.class, () -> mutNum.setValue(null));
     }
 
     @Test
@@ -112,18 +113,21 @@ public void testCompareTo() {
         assertEquals((byte) -1, mutNum.compareTo(new MutableByte((byte) 1)));
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testCompareToNull() {
         final MutableByte mutNum = new MutableByte((byte) 0);
-        mutNum.compareTo(null);
+        assertThrows(NullPointerException.class, () -> mutNum.compareTo(null));
     }
 
     @Test
     public void testPrimitiveValues() {
         final MutableByte mutNum = new MutableByte( (byte) 1 );
 
-        assertEquals( 1.0F, mutNum.floatValue(), 0 );
-        assertEquals( 1.0, mutNum.doubleValue(), 0 );
+        // TODO: JUnit Jupiter 5.3.1 doesn't support delta=0.
+        // This should be replaced when it is supported in JUnit Jupiter 5.4.
+        // See https://github.com/junit-team/junit5/pull/1613 for details.
+        assertTrue( 1.0F == mutNum.floatValue() );
+        assertTrue( 1.0 == mutNum.doubleValue() );
         assertEquals( (byte) 1, mutNum.byteValue() );
         assertEquals( (short) 1, mutNum.shortValue() );
         assertEquals( 1, mutNum.intValue() );
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableDoubleTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableDoubleTest.java
index df1b6d54c..378379a06 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableDoubleTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableDoubleTest.java
@@ -16,11 +16,12 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * JUnit tests.
@@ -43,9 +44,9 @@ public void testConstructors() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testConstructorNull() {
-        new MutableDouble((Number)null);
+        assertThrows(NullPointerException.class, () -> new MutableDouble((Number)null));
     }
 
     @Test
@@ -67,10 +68,10 @@ public void testGetSet() {
         assertEquals(Double.valueOf(3d), mutNum.getValue());
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testSetNull() {
         final MutableDouble mutNum = new MutableDouble(0d);
-        mutNum.setValue(null);
+        assertThrows(NullPointerException.class, () -> mutNum.setValue(null));
     }
 
     @Test
@@ -124,18 +125,21 @@ public void testCompareTo() {
         assertEquals(-1, mutNum.compareTo(new MutableDouble(1d)));
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testCompareToNull() {
         final MutableDouble mutNum = new MutableDouble(0d);
-        mutNum.compareTo(null);
+        assertThrows(NullPointerException.class, () -> mutNum.compareTo(null));
     }
 
     @Test
     public void testPrimitiveValues() {
         final MutableDouble mutNum = new MutableDouble(1.7);
 
-        assertEquals( 1.7F, mutNum.floatValue(), 0 );
-        assertEquals( 1.7, mutNum.doubleValue(), 0 );
+        // TODO: JUnit Jupiter 5.3.1 doesn't support delta=0.
+        // This should be replaced when it is supported in JUnit Jupiter 5.4.
+        // See https://github.com/junit-team/junit5/pull/1613 for details.
+        assertTrue ( 1.7F == mutNum.floatValue() );
+        assertTrue( 1.7 == mutNum.doubleValue() );
         assertEquals( (byte) 1, mutNum.byteValue() );
         assertEquals( (short) 1, mutNum.shortValue() );
         assertEquals( 1, mutNum.intValue() );
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableFloatTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableFloatTest.java
index 169763a50..96fbcdd65 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableFloatTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableFloatTest.java
@@ -16,11 +16,12 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * JUnit tests.
@@ -43,9 +44,9 @@ public void testConstructors() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testConstructorNull() {
-        new MutableFloat((Number)null);
+        assertThrows(NullPointerException.class, () -> new MutableFloat((Number)null));
     }
 
     @Test
@@ -67,10 +68,10 @@ public void testGetSet() {
         assertEquals(Float.valueOf(3f), mutNum.getValue());
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testSetNull() {
         final MutableFloat mutNum = new MutableFloat(0f);
-        mutNum.setValue(null);
+        assertThrows(NullPointerException.class, () -> mutNum.setValue(null));
     }
 
     @Test
@@ -124,10 +125,10 @@ public void testCompareTo() {
         assertEquals(-1, mutNum.compareTo(new MutableFloat(1f)));
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testCompareToNull() {
         final MutableFloat mutNum = new MutableFloat(0f);
-        mutNum.compareTo(null);
+        assertThrows(NullPointerException.class, () -> mutNum.compareTo(null));
     }
 
     @Test
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableIntTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableIntTest.java
index 9cf711edf..f3100d3e8 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableIntTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableIntTest.java
@@ -16,11 +16,12 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * JUnit tests.
@@ -43,9 +44,9 @@ public void testConstructors() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testConstructorNull() {
-        new MutableInt((Number)null);
+        assertThrows(NullPointerException.class, () -> new MutableInt((Number)null));
     }
 
     @Test
@@ -67,10 +68,10 @@ public void testGetSet() {
         assertEquals(Integer.valueOf(3), mutNum.getValue());
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testSetNull() {
         final MutableInt mutNum = new MutableInt(0);
-        mutNum.setValue(null);
+        assertThrows(NullPointerException.class, () -> mutNum.setValue(null));
     }
 
     @Test
@@ -119,20 +120,23 @@ public void testCompareTo() {
         assertEquals(-1, mutNum.compareTo(new MutableInt(1)));
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testCompareToNull() {
         final MutableInt mutNum = new MutableInt(0);
-        mutNum.compareTo(null);
+        assertThrows(NullPointerException.class, () -> mutNum.compareTo(null));
     }
 
     @Test
     public void testPrimitiveValues() {
         final MutableInt mutNum = new MutableInt(1);
 
+        // TODO: JUnit Jupiter 5.3.1 doesn't support delta=0.
+        // This should be replaced when it is supported in JUnit Jupiter 5.4.
+        // See https://github.com/junit-team/junit5/pull/1613 for details.
         assertEquals( (byte) 1, mutNum.byteValue() );
         assertEquals( (short) 1, mutNum.shortValue() );
-        assertEquals( 1.0F, mutNum.floatValue(), 0 );
-        assertEquals( 1.0, mutNum.doubleValue(), 0 );
+        assertTrue( 1.0F == mutNum.floatValue() );
+        assertTrue( 1.0 == mutNum.doubleValue() );
         assertEquals( 1L, mutNum.longValue() );
     }
 
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableLongTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableLongTest.java
index 1ec522e5c..2ad7ea9ad 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableLongTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableLongTest.java
@@ -16,11 +16,12 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * JUnit tests.
@@ -43,9 +44,9 @@ public void testConstructors() {
 
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testConstructorNull() {
-        new MutableLong((Number)null);
+        assertThrows(NullPointerException.class, () -> new MutableLong((Number)null));
     }
 
     @Test
@@ -67,10 +68,10 @@ public void testGetSet() {
         assertEquals(Long.valueOf(3), mutNum.getValue());
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testSetNull() {
         final MutableLong mutNum = new MutableLong(0);
-        mutNum.setValue(null);
+        assertThrows(NullPointerException.class, () -> mutNum.setValue(null));
     }
 
     @Test
@@ -112,18 +113,21 @@ public void testCompareTo() {
         assertEquals(-1, mutNum.compareTo(new MutableLong(1)));
     }
 
-    @Test(expected=NullPointerException.class)
+    @Test
     public void testCompareToNull() {
         final MutableLong mutNum = new MutableLong(0);
-        mutNum.compareTo(null);
+        assertThrows(NullPointerException.class, () -> mutNum.compareTo(null));
     }
 
     @Test
     public void testPrimitiveValues() {
         final MutableLong mutNum = new MutableLong(1L);
 
-        assertEquals( 1.0F, mutNum.floatValue(), 0 );
-        assertEquals( 1.0, mutNum.doubleValue(), 0 );
+        // TODO: JUnit Jupiter 5.3.1 doesn't support delta=0.
+        // This should be replaced when it is supported in JUnit Jupiter 5.4.
+        // See https://github.com/junit-team/junit5/pull/1613 for details.
+        assertTrue( 1.0F == mutNum.floatValue() );
+        assertTrue ( 1.0 == mutNum.doubleValue() );
         assertEquals( (byte) 1, mutNum.byteValue() );
         assertEquals( (short) 1, mutNum.shortValue() );
         assertEquals( 1, mutNum.intValue() );
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableObjectTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableObjectTest.java
index 09e9b7d8c..cbef25406 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableObjectTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableObjectTest.java
@@ -16,13 +16,13 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 
 /**
diff --git a/src/test/java/org/apache/commons/lang3/mutable/MutableShortTest.java b/src/test/java/org/apache/commons/lang3/mutable/MutableShortTest.java
index fe926fff6..85373c5a6 100644
--- a/src/test/java/org/apache/commons/lang3/mutable/MutableShortTest.java
+++ b/src/test/java/org/apache/commons/lang3/mutable/MutableShortTest.java
@@ -16,12 +16,12 @@
  */
 package org.apache.commons.lang3.mutable;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 /**
  * JUnit tests.
@@ -118,8 +118,11 @@ public void testCompareTo() {
     public void testPrimitiveValues() {
         final MutableShort mutNum = new MutableShort( (short) 1 );
 
-        assertEquals( 1.0F, mutNum.floatValue(), 0 );
-        assertEquals( 1.0, mutNum.doubleValue(), 0 );
+        // TODO: JUnit Jupiter 5.3.1 doesn't support delta=0.
+        // This should be replaced when it is supported in JUnit Jupiter 5.4.
+        // See https://github.com/junit-team/junit5/pull/1613 for details.
+        assertTrue ( 1.0F == mutNum.floatValue() );
+        assertTrue ( 1.0 == mutNum.doubleValue() );
         assertEquals( (byte) 1, mutNum.byteValue() );
         assertEquals( (short) 1, mutNum.shortValue() );
         assertEquals( 1, mutNum.intValue() );