diff --git a/frontends/amiga/gui.c b/frontends/amiga/gui.c
index 4b6daa778..657227459 100644
--- a/frontends/amiga/gui.c
+++ b/frontends/amiga/gui.c
@@ -17,10 +17,11 @@
  */
 
 
-
+#ifdef __amigaos4__
 /* Custom StringView class */
 #include "amiga/stringview/stringview.h"
 #include "amiga/stringview/urlhistory.h"
+#endif
 
 /* AmigaOS libraries */
 #ifdef __amigaos4__
@@ -196,7 +197,9 @@ static bool ami_quit = false;
 
 static struct MsgPort *schedulermsgport = NULL;
 static struct MsgPort *appport;
+#ifdef __amigaos4__
 static Class *urlStringClass;
+#endif
 
 static BOOL locked_screen = FALSE;
 static int screen_signal = -1;
@@ -439,7 +442,9 @@ static void ami_gui_resources_free(void)
 
 static bool ami_gui_resources_open(void)
 {
+#ifdef __amigaos4__
 	urlStringClass = MakeStringClass();
+#endif
 
     if(!(appport = AllocSysObjectTags(ASOT_PORT,
 							ASO_NoTrack, FALSE,
@@ -3058,7 +3063,9 @@ static void gui_quit(void)
 
 	ami_file_req_free();
 	ami_openurl_close();
+#ifdef __amigaos4__
 	FreeStringClass(urlStringClass);
+#endif
 
 	FreeObjList(window_list);
 
diff --git a/frontends/amiga/libs.c b/frontends/amiga/libs.c
index 4c242d214..30694542c 100644
--- a/frontends/amiga/libs.c
+++ b/frontends/amiga/libs.c
@@ -254,29 +254,32 @@ bool ami_libs_open(void)
 	 * NB: the last argument should be "true" only if the class also has
 	 * library functions we use.
 	 */
-	AMINS_CLASS_OPEN("arexx.class",                  44, ARexx,         AREXX,         false)
-	AMINS_CLASS_OPEN("images/bevel.image",           44, Bevel,         BEVEL,         false)
-	AMINS_CLASS_OPEN("images/bitmap.image",          44, BitMap,        BITMAP,        false)
-	AMINS_CLASS_OPEN("gadgets/button.gadget",        44, Button,        BUTTON,        false)
-	AMINS_CLASS_OPEN("gadgets/checkbox.gadget",      44, CheckBox,      CHECKBOX,      false)
-	AMINS_CLASS_OPEN("gadgets/chooser.gadget",       44, Chooser,       CHOOSER,       true)
-	AMINS_CLASS_OPEN("gadgets/clicktab.gadget",      44, ClickTab,      CLICKTAB,      true)
-	AMINS_CLASS_OPEN("gadgets/fuelgauge.gadget",     44, FuelGauge,     FUELGAUGE,     false)
-	AMINS_CLASS_OPEN("gadgets/getfile.gadget",       44, GetFile,       GETFILE,       false)
-	AMINS_CLASS_OPEN("gadgets/getfont.gadget",       44, GetFont,       GETFONT,       false)
-	AMINS_CLASS_OPEN("gadgets/getscreenmode.gadget", 44, GetScreenMode, GETSCREENMODE, false)
-	AMINS_CLASS_OPEN("gadgets/integer.gadget",       44, Integer,       INTEGER,       false)
-	AMINS_CLASS_OPEN("images/label.image",           44, Label,         LABEL,         false)
-	AMINS_CLASS_OPEN("gadgets/layout.gadget",        44, Layout,        LAYOUT,        true)
-	AMINS_CLASS_OPEN("gadgets/listbrowser.gadget",   44, ListBrowser,   LISTBROWSER,   true)
-	AMINS_CLASS_OPEN("gadgets/radiobutton.gadget",   44, RadioButton,   RADIOBUTTON,   false)
-	AMINS_CLASS_OPEN("gadgets/scroller.gadget",      44, Scroller,      SCROLLER,      false)
-	AMINS_CLASS_OPEN("gadgets/space.gadget",         44, Space,         SPACE,         false)
-	AMINS_CLASS_OPEN("gadgets/speedbar.gadget",      44, SpeedBar,      SPEEDBAR,      true)
-	AMINS_CLASS_OPEN("gadgets/string.gadget",        44, String,        STRING,        false)
-	AMINS_CLASS_OPEN("window.class",                 44, Window,        WINDOW,        false)
+	AMINS_CLASS_OPEN("arexx.class",                  41, ARexx,         AREXX,         false)
+	AMINS_CLASS_OPEN("images/bevel.image",           41, Bevel,         BEVEL,         false)
+	AMINS_CLASS_OPEN("images/bitmap.image",          41, BitMap,        BITMAP,        false)
+	AMINS_CLASS_OPEN("gadgets/button.gadget",        42, Button,        BUTTON,        false)
+	AMINS_CLASS_OPEN("gadgets/checkbox.gadget",      41, CheckBox,      CHECKBOX,      false)
+	AMINS_CLASS_OPEN("gadgets/chooser.gadget",       41, Chooser,       CHOOSER,       true)
+	AMINS_CLASS_OPEN("gadgets/clicktab.gadget",      42, ClickTab,      CLICKTAB,      true)
+	AMINS_CLASS_OPEN("gadgets/fuelgauge.gadget",     41, FuelGauge,     FUELGAUGE,     false)
+	AMINS_CLASS_OPEN("gadgets/getfile.gadget",       41, GetFile,       GETFILE,       false)
+	AMINS_CLASS_OPEN("gadgets/getfont.gadget",       41, GetFont,       GETFONT,       false)
+	AMINS_CLASS_OPEN("gadgets/getscreenmode.gadget", 41, GetScreenMode, GETSCREENMODE, false)
+	AMINS_CLASS_OPEN("gadgets/integer.gadget",       41, Integer,       INTEGER,       false)
+	AMINS_CLASS_OPEN("images/label.image",           41, Label,         LABEL,         false)
+	AMINS_CLASS_OPEN("gadgets/layout.gadget",        43, Layout,        LAYOUT,        true)
+	AMINS_CLASS_OPEN("gadgets/radiobutton.gadget",   41, RadioButton,   RADIOBUTTON,   false)
+	AMINS_CLASS_OPEN("gadgets/scroller.gadget",      42, Scroller,      SCROLLER,      false)
+	AMINS_CLASS_OPEN("gadgets/space.gadget",         41, Space,         SPACE,         false)
+	AMINS_CLASS_OPEN("gadgets/speedbar.gadget",      41, SpeedBar,      SPEEDBAR,      true)
+	AMINS_CLASS_OPEN("gadgets/string.gadget",        41, String,        STRING,        false)
+	AMINS_CLASS_OPEN("window.class",                 42, Window,        WINDOW,        false)
 
-#ifndef __amigaos4__
+#ifdef __amigaos4__
+	/* BOOPSI classes only required on OS4 */
+	AMINS_CLASS_OPEN("gadgets/listbrowser.gadget",   45, ListBrowser,   LISTBROWSER,   true)
+#else
+	/* BOOPSI classes only required prior to OS4 */
 	PageClass = PAGE_GetClass();
 #endif
 
@@ -302,13 +305,15 @@ void ami_libs_close(void)
 	AMINS_CLASS_CLOSE(Integer)
 	AMINS_CLASS_CLOSE(Label)
 	AMINS_CLASS_CLOSE(Layout)
-	AMINS_CLASS_CLOSE(ListBrowser)
 	AMINS_CLASS_CLOSE(RadioButton)
 	AMINS_CLASS_CLOSE(Scroller)
 	AMINS_CLASS_CLOSE(Space)
 	AMINS_CLASS_CLOSE(SpeedBar)
 	AMINS_CLASS_CLOSE(String)
 	AMINS_CLASS_CLOSE(Window)
+#ifdef __amigaos4__
+	AMINS_CLASS_CLOSE(ListBrowser)
+#endif
 
 	/* Libraries */
 	AMINS_LIB_CLOSE(GuiGFX)
diff --git a/frontends/amiga/stringview/stringview.c b/frontends/amiga/stringview/stringview.c
index e875f3b5a..245782b43 100755
--- a/frontends/amiga/stringview/stringview.c
+++ b/frontends/amiga/stringview/stringview.c
@@ -17,6 +17,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#ifdef __amigaos4__
 /// Include
 
 #include <proto/dos.h>
@@ -32,7 +33,6 @@
 #include <gadgets/layout.h>
 #include <gadgets/listbrowser.h>
 
-#include "amiga/os3support.h"
 #include "amiga/libs.h"
 
 #include "stringview.h"
@@ -867,4 +867,5 @@ void FreeStringClass(Class *cl)
 ///
 
 /* The End */
+#endif //__amigaos4__
 
diff --git a/frontends/amiga/stringview/stringview.h b/frontends/amiga/stringview/stringview.h
index f989b2a0f..776705f0f 100755
--- a/frontends/amiga/stringview/stringview.h
+++ b/frontends/amiga/stringview/stringview.h
@@ -17,7 +17,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "amiga/os3support.h"
+#ifndef AMIGA_STRINGVIEW_H
+#define AMIGA_STRINGVIEW_H 1
 
 #include <exec/semaphores.h>
 #include <intuition/classes.h>
@@ -58,3 +59,5 @@ void FreeStringClass(Class *);
 #ifdef __cplusplus
 }
 #endif
+#endif
+
diff --git a/frontends/amiga/stringview/urlhistory.c b/frontends/amiga/stringview/urlhistory.c
index 7405fbb57..c1e37ea7e 100644
--- a/frontends/amiga/stringview/urlhistory.c
+++ b/frontends/amiga/stringview/urlhistory.c
@@ -18,6 +18,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#ifdef __amigaos4__
 #include <stdio.h>
 #include <ctype.h>
 #include <string.h>
@@ -123,3 +124,5 @@ void URLHistory_AddPage( const char * urlString )
 		urldb_iterate_partial(urlString, URLHistoryFound);
 	}
 }
+#endif //__amigaos4__
+
diff --git a/frontends/amiga/stringview/urlhistory.h b/frontends/amiga/stringview/urlhistory.h
index b72792db4..962713e9e 100644
--- a/frontends/amiga/stringview/urlhistory.h
+++ b/frontends/amiga/stringview/urlhistory.h
@@ -17,6 +17,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#ifndef AMIGA_URLHISTORY_H
+#define AMIGA_URLHISTORY_H 1
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -31,3 +34,5 @@ void          URLHistory_AddPage( const char * urlString );
 #ifdef __cplusplus
 }
 #endif
+#endif
+