diff --git a/include/mapnik/unicode.hpp b/include/mapnik/unicode.hpp
index e2b109047..3b6d66498 100644
--- a/include/mapnik/unicode.hpp
+++ b/include/mapnik/unicode.hpp
@@ -43,7 +43,6 @@ public:
     mapnik::value_unicode_string transcode(const char* data, std::int32_t length = -1) const;
     ~transcoder();
 private:
-    bool ok_;
     UConverter * conv_;
 };
 }
diff --git a/src/unicode.cpp b/src/unicode.cpp
index 6fecf72da..c6a012bc1 100644
--- a/src/unicode.cpp
+++ b/src/unicode.cpp
@@ -34,13 +34,15 @@
 namespace mapnik {
 
 transcoder::transcoder (std::string const& encoding)
-    : ok_(false),
-      conv_(0)
+    : conv_(0)
 {
     UErrorCode err = U_ZERO_ERROR;
     conv_ = ucnv_open(encoding.c_str(),&err);
-    if (U_SUCCESS(err)) ok_ = true;
-    // TODO ??
+    if (!U_SUCCESS(err))
+    {
+        // NOT: conv_ should be null on error so no need to call ucnv_close
+        throw std::runtime_error(std::string("could not create converter for ") + encoding);
+    }
 }
 
 mapnik::value_unicode_string transcoder::transcode(const char* data, std::int32_t length) const
diff --git a/tests/cpp_tests/exceptions_test.cpp b/tests/cpp_tests/exceptions_test.cpp
index cc731fd9f..1bfc826e0 100644
--- a/tests/cpp_tests/exceptions_test.cpp
+++ b/tests/cpp_tests/exceptions_test.cpp
@@ -1,6 +1,7 @@
 #include <boost/detail/lightweight_test.hpp>
 #include <iostream>
 #include <mapnik/projection.hpp>
+#include <mapnik/unicode.hpp>
 #include <mapnik/map.hpp>
 #include <mapnik/save_map.hpp>
 #include <mapnik/graphics.hpp>
@@ -53,6 +54,13 @@ int main(int argc, char** argv)
         BOOST_TEST(true);
     }
 
+    try {
+        mapnik::transcoder tr("bogus encoding");
+        BOOST_TEST(false);
+    } catch (...) {
+        BOOST_TEST(true);
+    }
+
     mapnik::Map map(256,256);
     mapnik::rule r;
     r.set_filter(mapnik::parse_expression("[foo]='bar'"));