diff --git a/src/hammer.h b/src/hammer.h
index 62b5676610415b0a03a9546cea7b829b3477d658..3d21c7b85ab709e5a392ec55f9b8f2e42897cb1f 100644
--- a/src/hammer.h
+++ b/src/hammer.h
@@ -224,6 +224,13 @@ const HParser* h_whitespace(const HParser* p);
  */
 const HParser* h_action(const HParser* p, const HAction a);
 
+/**
+ * Parse a single character in the given charset. 
+ *
+ * Result token type: TT_UINT
+ */
+const HParser* h_in(const uint8_t *charset, size_t length);
+
 /**
  * Parse a single character *NOT* in the given charset. 
  *
diff --git a/src/parsers/charset.c b/src/parsers/charset.c
index 6420af501a2b0058731f1d5bd6c6678620378d46..b9642fccd0aef2394f64de70fed56e911a918ad9 100644
--- a/src/parsers/charset.c
+++ b/src/parsers/charset.c
@@ -28,16 +28,24 @@ const HParser* h_ch_range(const uint8_t lower, const uint8_t upper) {
 }
 
 
-const HParser* h_not_in(const uint8_t *options, size_t count) {
+const HParser* h_in_or_not(const uint8_t *options, size_t count, int val) {
   HParser *ret = g_new(HParser, 1);
   HCharset cs = new_charset();
   for (size_t i = 0; i < 256; i++)
-    charset_set(cs, i, 1);
+    charset_set(cs, i, 1-val);
   for (size_t i = 0; i < count; i++)
-    charset_set(cs, options[i], 0);
+    charset_set(cs, options[i], val);
 
   ret->vtable = &charset_vt;
   ret->env = (void*)cs;
   return (const HParser*)ret;
 }
 
+const HParser* h_in(const uint8_t *options, size_t count) {
+  return h_in_or_not(options, count, 1);
+}
+
+const HParser* h_not_in(const uint8_t *options, size_t count) {
+  return h_in_or_not(options, count, 0);
+}
+