diff --git a/src/main/java/com/github/zafarkhaja/semver/VersionParser.java b/src/main/java/com/github/zafarkhaja/semver/VersionParser.java
index 1911e61..25d1c5f 100644
--- a/src/main/java/com/github/zafarkhaja/semver/VersionParser.java
+++ b/src/main/java/com/github/zafarkhaja/semver/VersionParser.java
@@ -26,6 +26,7 @@ package com.github.zafarkhaja.semver;
 import com.github.zafarkhaja.semver.util.Stream;
 import com.github.zafarkhaja.semver.util.UnexpectedElementException;
 import java.util.ArrayList;
+import java.util.EnumSet;
 import java.util.List;
 import static com.github.zafarkhaja.semver.VersionParser.CharType.*;
 
@@ -111,6 +112,21 @@ class VersionParser implements Parser<Version> {
             public boolean isMatchedBy(Character chr) {
                 return chr == null;
             }
+        },
+        ILLEGAL {
+            /**
+             * {@inheritDoc}
+             */
+            @Override
+            public boolean isMatchedBy(Character chr) {
+                EnumSet<CharType> itself = EnumSet.of(ILLEGAL);
+                for (CharType type : EnumSet.complementOf(itself)) {
+                    if (type.isMatchedBy(chr)) {
+                        return false;
+                    }
+                }
+                return true;
+            }
         };
     }
 
diff --git a/src/test/java/com/github/zafarkhaja/semver/VersionParserCharTypeTest.java b/src/test/java/com/github/zafarkhaja/semver/VersionParserCharTypeTest.java
index a979436..4eb4d0d 100644
--- a/src/test/java/com/github/zafarkhaja/semver/VersionParserCharTypeTest.java
+++ b/src/test/java/com/github/zafarkhaja/semver/VersionParserCharTypeTest.java
@@ -80,4 +80,12 @@ public class VersionParserCharTypeTest {
         assertFalse(EOL.isMatchedBy('a'));
         assertFalse(EOL.isMatchedBy('0'));
     }
+
+    @Test
+    public void shouldBeMatchedByIllegal() {
+        assertTrue(ILLEGAL.isMatchedBy('!'));
+        assertFalse(ILLEGAL.isMatchedBy('-'));
+        assertFalse(ILLEGAL.isMatchedBy('a'));
+        assertFalse(ILLEGAL.isMatchedBy('0'));
+    }
 }