diff --git a/test/test_lexers.jl b/test/test_lexers.jl
index 882ddc4..b3c0017 100644
--- a/test/test_lexers.jl
+++ b/test/test_lexers.jl
@@ -64,11 +64,11 @@ end
         lexer_test("\"a\"", Tokens.STRING_LIT)
         lexer_test("'a'", Tokens.STRING_LIT)
         lexer_test("\"proto3\"", Tokens.STRING_LIT)
-        lexer_test("'\uffff'", Tokens.STRING_LIT)
-        lexer_test("'\xff'", Tokens.STRING_LIT)
-        lexer_test("'\777'", Tokens.STRING_LIT)
-        lexer_test("'\U000fffff'", Tokens.STRING_LIT)
-        lexer_test("'\U0010ffff'", Tokens.STRING_LIT)
+        lexer_test(raw"'\uffff'", Tokens.STRING_LIT)
+        lexer_test(raw"'\xff'", Tokens.STRING_LIT)
+        lexer_test(raw"'\777'", Tokens.STRING_LIT)
+        lexer_test(raw"'\U000fffff'", Tokens.STRING_LIT)
+        lexer_test(raw"'\U0010ffff'", Tokens.STRING_LIT)
     end
 
     @testset "numeric literals" begin
@@ -223,4 +223,4 @@ end
             lexer_test(w, KEYWORDS_AND_TYPES[w])
         end
     end
-end
\ No newline at end of file
+end