diff --git a/include/wx/wxcrt.h b/include/wx/wxcrt.h
index b99543cf3b..9eccfe4cb0 100644
--- a/include/wx/wxcrt.h
+++ b/include/wx/wxcrt.h
@@ -987,4 +987,6 @@ wxDEPRECATED( inline int wxIsctrl(const wxUniChar& c) );
 inline int wxIsctrl(const wxUniChar& c) { return wxIscntrl(c); }
 #endif // WXWIN_COMPATIBILITY_2_8
 
+inline bool wxIsascii(const wxUniChar& c) { return c.IsAscii(); }
+
 #endif /* _WX_WXCRT_H_ */
diff --git a/src/common/accelcmn.cpp b/src/common/accelcmn.cpp
index 611fdfd97f..ee99542df2 100644
--- a/src/common/accelcmn.cpp
+++ b/src/common/accelcmn.cpp
@@ -323,7 +323,9 @@ wxString wxAcceleratorEntry::ToString() const
             // must be a simple key
             if (
 #if !wxUSE_UNICODE
-                 isascii(code) &&
+                 // we can't call wxIsalnum() for non-ASCII characters in ASCII
+                 // build as they're only defined for the ASCII range (or EOF)
+                 wxIsascii(code) &&
 #endif // ANSI
                     wxIsalnum(code) )
             {
diff --git a/src/generic/accel.cpp b/src/generic/accel.cpp
index 29893831fe..15054cb158 100644
--- a/src/generic/accel.cpp
+++ b/src/generic/accel.cpp
@@ -94,8 +94,8 @@ wxAcceleratorTable::wxAcceleratorTable(int n, const wxAcceleratorEntry entries[]
         const wxAcceleratorEntry& entry = entries[i];
 
         int keycode = entry.GetKeyCode();
-        if ( isascii(keycode) )
-            keycode = toupper(keycode);
+        if ( wxIsascii(keycode) )
+            keycode = wxToupper(keycode);
 
         M_ACCELDATA->m_accels.Append(new wxAcceleratorEntry(entry.GetFlags(),
                                                             keycode,
diff --git a/src/generic/grideditors.cpp b/src/generic/grideditors.cpp
index c07eb13722..6ec2505ac8 100644
--- a/src/generic/grideditors.cpp
+++ b/src/generic/grideditors.cpp
@@ -1027,13 +1027,8 @@ bool wxGridCellFloatEditor::IsAcceptedKey(wxKeyEvent& event)
     if ( wxGridCellEditor::IsAcceptedKey(event) )
     {
         const int keycode = event.GetKeyCode();
-        if ( isascii(keycode) )
+        if ( wxIsascii(keycode) )
         {
-            char tmpbuf[2];
-            tmpbuf[0] = (char) keycode;
-            tmpbuf[1] = '\0';
-            wxString strbuf(tmpbuf, *wxConvCurrent);
-
 #if wxUSE_INTL
             const wxString decimalPoint =
                 wxLocale::GetInfo(wxLOCALE_DECIMAL_POINT, wxLOCALE_CAT_NUMBER);
diff --git a/src/generic/helpext.cpp b/src/generic/helpext.cpp
index b6e4b63812..4f1f2543c4 100644
--- a/src/generic/helpext.cpp
+++ b/src/generic/helpext.cpp
@@ -172,7 +172,7 @@ bool wxExtHelpController::ParseMapFileLine(const wxString& line)
     const wxChar *p = line.c_str();
 
     // skip whitespace
-    while ( isascii(*p) && isspace(*p) )
+    while ( isascii(*p) && wxIsspace(*p) )
         p++;
 
     // skip empty lines and comments
@@ -187,16 +187,16 @@ bool wxExtHelpController::ParseMapFileLine(const wxString& line)
         return false;
 
     p = end;
-    while ( isascii(*p) && isspace(*p) )
+    while ( isascii(*p) && wxIsspace(*p) )
         p++;
 
     // next should be the URL
     wxString url;
     url.reserve(line.length());
-    while ( isascii(*p) && !isspace(*p) )
+    while ( isascii(*p) && !wxIsspace(*p) )
         url += *p++;
 
-    while ( isascii(*p) && isspace(*p) )
+    while ( isascii(*p) && wxIsspace(*p) )
         p++;
 
     // and finally the optional description of the entry after comment
@@ -204,7 +204,7 @@ bool wxExtHelpController::ParseMapFileLine(const wxString& line)
     if ( *p == WXEXTHELP_COMMENTCHAR )
     {
         p++;
-        while ( isascii(*p) && isspace(*p) )
+        while ( isascii(*p) && wxIsspace(*p) )
             p++;
         doc = p;
     }
diff --git a/src/motif/accel.cpp b/src/motif/accel.cpp
index 3aad0fb5b5..ba59df93dd 100644
--- a/src/motif/accel.cpp
+++ b/src/motif/accel.cpp
@@ -108,8 +108,8 @@ bool wxAcceleratorEntry::MatchesEvent(const wxKeyEvent& event) const
     bool accShiftDown = ((GetFlags() & wxACCEL_SHIFT) == wxACCEL_SHIFT);
     int  accKeyCode = GetKeyCode();
     int  accKeyCode2 = GetKeyCode();
-    if (isascii(accKeyCode2))
-        accKeyCode2 = tolower(accKeyCode2);
+    if (wxIsascii(accKeyCode2))
+        accKeyCode2 = wxTolower(accKeyCode2);
 
     return ((eventAltDown == accAltDown) && (eventCtrlDown == accCtrlDown) &&
         (eventShiftDown == accShiftDown) &&
diff --git a/src/motif/textctrl.cpp b/src/motif/textctrl.cpp
index 92ea827279..4cd726bc04 100644
--- a/src/motif/textctrl.cpp
+++ b/src/motif/textctrl.cpp
@@ -387,7 +387,7 @@ void wxTextCtrl::OnChar(wxKeyEvent& event)
         XmTextVerifyCallbackStruct *textStruct =
             (XmTextVerifyCallbackStruct *) m_tempCallbackStruct;
         textStruct->doit = True;
-        if (isascii(event.m_keyCode) && (textStruct->text->length == 1))
+        if (wxIsascii(event.m_keyCode) && (textStruct->text->length == 1))
         {
             textStruct->text->ptr[0] = (char)((event.m_keyCode == WXK_RETURN) ? 10 : event.m_keyCode);
         }