diff --git a/mysys/my_getopt.c b/mysys/my_getopt.c
index 6e9c6334620..653fe844093 100644
--- a/mysys/my_getopt.c
+++ b/mysys/my_getopt.c
@@ -163,11 +163,6 @@ static void validate_value(const char *key, const char *value,
   }
   else
   {
-    /*
-     Should never happen, non-UTF8 can be read from option's
-     file only.
-    */
-    DBUG_ASSERT(0);
     my_getopt_error_reporter(
     WARNING_LEVEL, "%s: invalid (non-UTF8) characters for option %s",
       my_progname, key);
diff --git a/sql/upgrade_conf_file.cc b/sql/upgrade_conf_file.cc
index 9a19dd8b8a2..0d7bc603468 100644
--- a/sql/upgrade_conf_file.cc
+++ b/sql/upgrade_conf_file.cc
@@ -288,7 +288,7 @@ static bool is_mariadb_section(const char *name, bool *is_server)
     if (*is_server= !strcmp(section_name, name))
       break;
 
-  return *is_server;
+  return true;
 }
 
 
diff --git a/win/upgrade_wizard/upgradeDlg.cpp b/win/upgrade_wizard/upgradeDlg.cpp
index 7aae4890b51..10a1787c231 100644
--- a/win/upgrade_wizard/upgradeDlg.cpp
+++ b/win/upgrade_wizard/upgradeDlg.cpp
@@ -15,6 +15,7 @@
 #include <vector>
 
 #include <winservice.h>
+#include <locale.h>
 
 using namespace std;
 
@@ -271,6 +272,11 @@ BOOL CUpgradeDlg::OnInitDialog()
 
   m_Progress.ShowWindow(SW_HIDE);
   m_Ok.EnableWindow(FALSE);
+  if (GetACP() == CP_UTF8)
+  {
+    /* Required for mbstowcs, used in some functions.*/
+    setlocale(LC_ALL, "en_US.UTF8");
+  }
   PopulateServicesList();
   return TRUE;  // return TRUE  unless you set the focus to a control
 }