diff --git a/CMakeLists.txt b/CMakeLists.txt
index ff9c652..cdafe45 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required (VERSION 3.2)
 project(identiconpp
-        VERSION 0.1.0
+        VERSION 0.1.1
         LANGUAGES CXX
 )
 
diff --git a/src/identiconpp.cpp b/src/identiconpp.cpp
index f8f2e2e..cc071e7 100644
--- a/src/identiconpp.cpp
+++ b/src/identiconpp.cpp
@@ -18,7 +18,7 @@
 #include <stdexcept>
 #include <sstream>
 #include <bitset>
-#include <iomanip>
+#include <algorithm>
 #include "identiconpp.hpp"
 #include "debug.hpp"
 
@@ -32,21 +32,11 @@ Identiconpp::Identiconpp(const uint8_t rows, const uint8_t columns,
 , _background(background)
 , _foreground(foreground)
 {
-    if (background.length() != 8)
-    {
-        throw std::invalid_argument
-        (
-            "The background color must consist of exactly 8 digits."
-        );
-    }
+    check_color(background);
 
     for (const string &color : foreground)
-    if (color.length() != 8)
     {
-        throw std::invalid_argument
-        (
-            "The foreground colors must consist of exactly 8 digits."
-        );
+        check_color(color);
     }
 }
 
@@ -194,3 +184,35 @@ Magick::Color Identiconpp::get_color(const uint16_t firstbit,
     ttdebug << "Color: #" << _foreground[bits - 1] << '\n';
     return Magick::Color("#" + _foreground[bits - 1]);
 }
+
+bool Identiconpp::not_hex(const char c)
+{
+    if (c >= 0x61 && c <= 0x66)
+    {   // a-f
+        return false;
+    }
+    if (c >= 0x30 && c <= 0x39)
+    {   // 0-9
+        return false;
+    }
+
+    return true;
+}
+
+void Identiconpp::check_color(const string &color)
+{
+    if (color.length() != 8)
+    {
+        throw std::invalid_argument
+        (
+            "Colors must consist of exactly 8 digits(" + color + ")."
+        );
+    }
+    if (std::any_of(color.begin(), color.end(), not_hex))
+    {
+        throw std::invalid_argument
+        (
+            "Colors must consist of hexadecimal digits (" + color + ")."
+        );
+    }
+}
diff --git a/src/identiconpp.hpp b/src/identiconpp.hpp
index b67ed7e..81ec234 100644
--- a/src/identiconpp.hpp
+++ b/src/identiconpp.hpp
@@ -61,7 +61,7 @@ public:
      *  @param  foreground  vector of foreground colors
      */
     explicit Identiconpp(const uint8_t rows, const uint8_t columns,
-                         identicon_type type,
+                         identicon_type type = identicon_type::simple,
                          const string background = "ffffffff",
                          const vector<string> &foreground = { "000000ff" } );
 
@@ -139,4 +139,20 @@ private:
      *  @return A foreground color.
      */
     Magick::Color get_color(const uint16_t firstbit, const string &digest);
+
+    /*!
+     *  @brief  Checks if character is not hexadecimal.
+     *
+     *  @param  c       Character to check
+     *
+     *  @return true if not hex.
+     */
+    static bool not_hex(const char c);
+
+    /*!
+     *  @brief  Performs checks on a color definition in a string.
+     *
+     *  @param  color   The color as string
+     */
+    void check_color(const string &color);
 };