diff --git a/plugins/input/csv/csv_datasource.cpp b/plugins/input/csv/csv_datasource.cpp
index 8b609b059..c02f1e20b 100644
--- a/plugins/input/csv/csv_datasource.cpp
+++ b/plugins/input/csv/csv_datasource.cpp
@@ -694,10 +694,7 @@ void csv_datasource::parse_csv(T & stream,
                         desc_.add_descriptor(mapnik::attribute_descriptor(fld_name,mapnik::String));
                     }
                 }
-                else if ((value[0] >= '0' && value[0] <= '9') ||
-                         value[0] == '-' ||
-                         value[0] == '+' ||
-                         value[0] == '.')
+                else if (csv_utils::is_likely_number(value))
                 {
                     bool has_e = value.find("e") != std::string::npos;
                     if (has_dot || has_e)
diff --git a/plugins/input/csv/csv_utils.hpp b/plugins/input/csv/csv_utils.hpp
index 3fdcaa3c8..fd9143fee 100644
--- a/plugins/input/csv/csv_utils.hpp
+++ b/plugins/input/csv/csv_utils.hpp
@@ -26,9 +26,15 @@
 
 #include <string>
 #include <boost/algorithm/string.hpp>
+#include <cstdio>
 
 namespace csv_utils
 {
+    static inline bool is_likely_number(std::string const& value)
+    {
+        return( strspn( value.c_str(), "e-.+0123456789" ) == value.size() );
+    }
+
     static inline void fix_json_quoting(std::string & csv_line)
     {
         std::string wrapping_char;