diff --git a/src/redempt/redlex/token/StringToken.java b/src/redempt/redlex/token/StringToken.java
index 4bd1bcc..316941e 100644
--- a/src/redempt/redlex/token/StringToken.java
+++ b/src/redempt/redlex/token/StringToken.java
@@ -2,6 +2,7 @@
 
 import redempt.redlex.data.TokenType;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
@@ -57,6 +58,12 @@ public int maxLength() {
 
 	@Override
 	public List<Character> calcFirstCharacters() {
+		if (!caseSensitive && string.length() > 0) {
+			List<Character> chars = new ArrayList<>();
+			chars.add(string.charAt(0));
+			chars.add(Character.toUpperCase(string.charAt(0)));
+			return chars;
+		}
 		return Collections.singletonList(string.length() == 0 ? null : string.charAt(0));
 	}
 
diff --git a/test/java/redempt/redlex/test/RedLexTest.java b/test/java/redempt/redlex/test/RedLexTest.java
index e23e167..77dfec9 100644
--- a/test/java/redempt/redlex/test/RedLexTest.java
+++ b/test/java/redempt/redlex/test/RedLexTest.java
@@ -118,6 +118,12 @@ public void caseInsensitiveTest() {
 		assertDoesNotThrow(() -> lexer.tokenize("aBc"));
 		assertDoesNotThrow(() -> lexer.tokenize("Abc"));
 		assertDoesNotThrow(() -> lexer.tokenize("ABC"));
+		
+		Lexer lexer2 = BNFParser.createLexer("root ::= \"abc\"");
+		assertDoesNotThrow(() -> lexer2.tokenize("abc"));
+		assertThrows(LexException.class, () -> lexer2.tokenize("Abc"));
+		assertThrows(LexException.class, () -> lexer2.tokenize("aBc"));
+		assertThrows(LexException.class, () -> lexer2.tokenize("aBC"));
 	}
 	
 }