diff --git a/src/main/java/org/apache/commons/lang3/math/NumberUtils.java b/src/main/java/org/apache/commons/lang3/math/NumberUtils.java
index 21e4079b9..240375cac 100644
--- a/src/main/java/org/apache/commons/lang3/math/NumberUtils.java
+++ b/src/main/java/org/apache/commons/lang3/math/NumberUtils.java
@@ -1344,7 +1344,7 @@ public static boolean isDigits(final String str) {
      * <code>false</code>, since <code>9</code> is not a valid octal value.
      * However, numbers beginning with {@code 0.} are treated as decimal.</p>
      *
-     * <p><code>Null</code> and empty String will return
+     * <p><code>null</code> and empty/blank {@code String} will return
      * <code>false</code>.</p>
      *
      * @param str  the <code>String</code> to check
diff --git a/src/test/java/org/apache/commons/lang3/math/NumberUtilsTest.java b/src/test/java/org/apache/commons/lang3/math/NumberUtilsTest.java
index 6ca18f1b8..7a99a0b33 100644
--- a/src/test/java/org/apache/commons/lang3/math/NumberUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/math/NumberUtilsTest.java
@@ -1199,6 +1199,8 @@ public void testIsNumber() {
 
         compareIsNumberWithCreateNumber(null, false);
         compareIsNumberWithCreateNumber("", false);
+        compareIsNumberWithCreateNumber(" ", false);
+        compareIsNumberWithCreateNumber("\r\n\t", false);
         compareIsNumberWithCreateNumber("--2.3", false);
         compareIsNumberWithCreateNumber(".12.3", false);
         compareIsNumberWithCreateNumber("-123E", false);