diff --git a/source/shared/core_stmt.cpp b/source/shared/core_stmt.cpp
index f3ffc3976..bef12f054 100644
--- a/source/shared/core_stmt.cpp
+++ b/source/shared/core_stmt.cpp
@@ -2496,6 +2496,12 @@ void sqlsrv_param::bind_param(_Inout_ sqlsrv_stmt* stmt)
 {
     if (was_null) {
         strlen_or_indptr = SQL_NULL_DATA;
+	if ((sql_data_type == SQL_CHAR) && (column_size == 1)) {
+	  // This is a work-around for a bug in Microsoft SQL Server and/or unixODBC and/or msodbcsql;
+	  // as to how the T-SQL operator ISNULL likes to see a NULL.
+	  sql_data_type = SQL_VARCHAR;
+	  column_size = 0;
+	}
     }
 
     core::SQLBindParameter(stmt, param_pos + 1, direction, c_data_type, sql_data_type, column_size, decimal_digits, buffer, buffer_length, &strlen_or_indptr);