diff --git a/.ci/pitest.sh b/.ci/pitest.sh
index 690bf9e82f88..31fad3c44d53 100755
--- a/.ci/pitest.sh
+++ b/.ci/pitest.sh
@@ -72,7 +72,6 @@ pitest-imports)
   mvn -e -P$1 clean test org.pitest:pitest-maven:mutationCoverage;
   declare -a ignoredItems=(
   "CustomImportOrderCheck.java.html:<td class='covered'><pre><span  class='survived'>        if (bestMatch.group.equals(NON_GROUP_RULE_GROUP)) {</span></pre></td></tr>"
-  "IllegalImportCheck.java.html:<td class='covered'><pre><span  class='survived'>        if (regexp) {</span></pre></td></tr>"
   "IllegalImportCheck.java.html:<td class='covered'><pre><span  class='survived'>        if (!result &#38;&#38; illegalClasses != null) {</span></pre></td></tr>"
   "IllegalImportCheck.java.html:<td class='covered'><pre><span  class='survived'>        if (!result) {</span></pre></td></tr>"
   "ImportControlLoader.java.html:<td class='covered'><pre><span  class='survived'>        else if (ALLOW_ELEMENT_NAME.equals(qName) || &#34;disallow&#34;.equals(qName)) {</span></pre></td></tr>"
@@ -225,6 +224,3 @@ pitest-utils)
   ;;
 
 esac
-
-
-
diff --git a/src/test/java/com/puppycrawl/tools/checkstyle/checks/imports/IllegalImportCheckTest.java b/src/test/java/com/puppycrawl/tools/checkstyle/checks/imports/IllegalImportCheckTest.java
index 80221d5d2dea..459835536412 100644
--- a/src/test/java/com/puppycrawl/tools/checkstyle/checks/imports/IllegalImportCheckTest.java
+++ b/src/test/java/com/puppycrawl/tools/checkstyle/checks/imports/IllegalImportCheckTest.java
@@ -93,6 +93,21 @@ public void testIllegalClasses()
         verify(checkConfig, getNonCompilablePath("InputIllegalImportDefault.java"), expected);
     }
 
+    @Test
+    public void testIllegalClasses1()
+            throws Exception {
+        final DefaultConfiguration checkConfig =
+            createModuleConfig(IllegalImportCheck.class);
+        checkConfig.addAttribute("illegalClasses", "java.io.*");
+        final String[] expected = {
+            "9:1: " + getCheckMessage(MSG_KEY, "java.io.*"),
+            "15:1: " + getCheckMessage(MSG_KEY, "sun.applet.*"),
+            "28:1: " + getCheckMessage(MSG_KEY, "sun.*"),
+        };
+        verify(checkConfig, getNonCompilablePath("InputIllegalImportDefault.java"), expected);
+    }
+
+
     @Test
     public void testIllegalPackagesRegularExpression()
             throws Exception {