diff --git a/CHANGELOG.md b/CHANGELOG.md
index dd5a382a..26289ca2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ## 9.0.0.1 - (In Progress)
 
-*  Add `iswblank` compatibility.
+*  Add `iswblank` and `iswxdigit` compatibility.
 
 ## 9.0.0 - 2016-12-28
 
diff --git a/README.md b/README.md
index ee0610f0..36e06e80 100644
--- a/README.md
+++ b/README.md
@@ -92,21 +92,20 @@ C library provides a set of APIs that are compatible with `wctype.h`.
 
 The following character classification functions are provided:
 
-| C API         | C++ API        |
-|---------------|----------------|
-| `ucd_isalnum` | `ucd::isalnum` |
-| `ucd_isalpha` | `ucd::isalpha` |
-| `ucd_isblank` | `ucd::isblank` |
-| `ucd_iscntrl` | `ucd::iscntrl` |
-| `ucd_isdigit` | `ucd::isdigit` |
-| `ucd_isgraph` | `ucd::isgraph` |
-| `ucd_islower` | `ucd::islower` |
-| `ucd_isprint` | `ucd::isprint` |
-| `ucd_ispunct` | `ucd::ispunct` |
-| `ucd_isspace` | `ucd::isspace` |
-| `ucd_isupper` | `ucd::isupper` |
-
-__NOTE:__ An equivalent for `isxdigit` is not provided.
+| C API          | C++ API         |
+|----------------|-----------------|
+| `ucd_isalnum`  | `ucd::isalnum`  |
+| `ucd_isalpha`  | `ucd::isalpha`  |
+| `ucd_isblank`  | `ucd::isblank`  |
+| `ucd_iscntrl`  | `ucd::iscntrl`  |
+| `ucd_isdigit`  | `ucd::isdigit`  |
+| `ucd_isgraph`  | `ucd::isgraph`  |
+| `ucd_islower`  | `ucd::islower`  |
+| `ucd_isprint`  | `ucd::isprint`  |
+| `ucd_ispunct`  | `ucd::ispunct`  |
+| `ucd_isspace`  | `ucd::isspace`  |
+| `ucd_isupper`  | `ucd::isupper`  |
+| `ucd_isxdigit` | `ucd::isxdigit` |
 
 ## Build Dependencies
 
diff --git a/src/ctype.c b/src/ctype.c
index f1be7643..30edfb93 100644
--- a/src/ctype.c
+++ b/src/ctype.c
@@ -169,3 +169,10 @@ int ucd_isupper(codepoint_t c)
 {
 	return ucd_lookup_category(c) == UCD_CATEGORY_Lu;
 }
+
+int ucd_isxdigit(codepoint_t c)
+{
+	return (c >= 0x30 && c <= 0x39)  // [0-9]
+	    || (c >= 0x41 && c <= 0x46)  // [A-Z]
+	    || (c >= 0x61 && c <= 0x66); // [a-z]
+}
diff --git a/src/include/ucd/ucd.h b/src/include/ucd/ucd.h
index 6693329c..b4bff02a 100644
--- a/src/include/ucd/ucd.h
+++ b/src/include/ucd/ucd.h
@@ -402,6 +402,13 @@ int ucd_isspace(codepoint_t c);
   */
 int ucd_isupper(codepoint_t c);
 
+/** @brief Is the codepoint in the 'xdigit' class?
+  *
+  * @param c The Unicode codepoint to check.
+  * @return  Non-zero if the codepoint is in the 'xdigit' class, zero otherwise.
+  */
+int ucd_isxdigit(codepoint_t c);
+
 /** @brief Convert the Unicode codepoint to upper-case.
   *
   * This function only uses the simple case mapping present in the
@@ -873,6 +880,16 @@ namespace ucd
 		return ucd_isupper(c);
 	}
 
+	/** @brief Is the codepoint in the 'xdigit' class?
+	  *
+	  * @param c The Unicode codepoint to check.
+	  * @return  Non-zero if the codepoint is in the 'xdigit' class, zero otherwise.
+	  */
+	inline int isxdigit(codepoint_t c)
+	{
+		return ucd_isxdigit(c);
+	}
+
 	/** @brief Convert the Unicode codepoint to upper-case.
 	  *
 	  * This function only uses the simple case mapping present in the
diff --git a/tests/printcdata.c b/tests/printcdata.c
index 8b19749a..24d57c92 100644
--- a/tests/printcdata.c
+++ b/tests/printcdata.c
@@ -141,6 +141,9 @@ void uprintf_is(FILE *out, codepoint_t c, char mode)
 	case 'u': // upper case
 		fputc(iswupper(c) ? '1' : '0', out);
 		break;
+	case 'x': // xdigit
+		fputc(iswxdigit(c) ? '1' : '0', out);
+		break;
 	}
 }
 
diff --git a/tests/printucddata.c b/tests/printucddata.c
index 9400b547..e397f12e 100644
--- a/tests/printucddata.c
+++ b/tests/printucddata.c
@@ -138,6 +138,9 @@ void uprintf_is(FILE *out, codepoint_t c, char mode)
 	case 'u': // upper case
 		fputc(ucd_isupper(c) ? '1' : '0', out);
 		break;
+	case 'x': // xdigit
+		fputc(ucd_isxdigit(c) ? '1' : '0', out);
+		break;
 	}
 }
 
diff --git a/tests/printucddata_cpp.cpp b/tests/printucddata_cpp.cpp
index 41e37605..2318b09a 100644
--- a/tests/printucddata_cpp.cpp
+++ b/tests/printucddata_cpp.cpp
@@ -138,6 +138,9 @@ void uprintf_is(FILE *out, ucd::codepoint_t c, char mode)
 	case 'u': // upper case
 		fputc(ucd::isupper(c) ? '1' : '0', out);
 		break;
+	case 'x': // xdigit
+		fputc(ucd::isxdigit(c) ? '1' : '0', out);
+		break;
 	}
 }