diff --git a/src/mred/mred.cxx b/src/mred/mred.cxx
index faaf2bf14f..b868a0f966 100644
--- a/src/mred/mred.cxx
+++ b/src/mred/mred.cxx
@@ -810,7 +810,7 @@ static MrEdContext *MakeContext(MrEdContext *c)
   }
   c->mr_hop = mr_hop;
 #ifndef MZ_PRECISE_GC
-  scheme_weak_reference((void **)&mr_hop->context);
+  scheme_weak_reference((void **)(void *)&mr_hop->context);
 #endif
 
   {
diff --git a/src/mred/wxme/wx_mpriv.cxx b/src/mred/wxme/wx_mpriv.cxx
index 917a7b6c72..4c9db11330 100644
--- a/src/mred/wxme/wx_mpriv.cxx
+++ b/src/mred/wxme/wx_mpriv.cxx
@@ -2720,7 +2720,7 @@ void wxMediaEdit::ContinueRefresh(void)
         rs =  0;
       } else {
         delayedscroll = -1;
-        delayedscrollbox = NULL;
+        delayedscrollbox = 0;
       }
     }
     if (admin && !admin->standard)
diff --git a/src/mred/wxme/wx_style.cxx b/src/mred/wxme/wx_style.cxx
index 750e2511f2..d7626e1cfc 100644
--- a/src/mred/wxme/wx_style.cxx
+++ b/src/mred/wxme/wx_style.cxx
@@ -1268,9 +1268,9 @@ void *wxStyleList::NotifyOnChange(wxStyleNotifyFunc f, void *data, int weak)
   } else {
     void *weak_data;
     weak_data = (void *)scheme_box((Scheme_Object *)data);
-    GC_finalization_weak_ptr((void **)weak_data, 
-			     ((void **)&SCHEME_BOX_VAL(weak_data)
-			      - (void **)weak_data));
+    GC_finalization_weak_ptr((void **)(void *)weak_data, 
+			     ((void **)(void *)&SCHEME_BOX_VAL(weak_data)
+			      - (void **)(void *)weak_data));
     rec->data = weak_data;
   }
 #else
@@ -1280,7 +1280,7 @@ void *wxStyleList::NotifyOnChange(wxStyleNotifyFunc f, void *data, int weak)
     rec = new WXGC_PTRS NotificationRec;
   rec->data = data;
   if (weak)
-    scheme_weak_reference((void **)&rec->data);
+    scheme_weak_reference((void **)(void *)&rec->data);
   else
     WXGC_IGNORE(rec, rec->data);
 #endif
diff --git a/src/mred/wxs/wxscheme.cxx b/src/mred/wxs/wxscheme.cxx
index 4f092ee46c..567b0848a6 100644
--- a/src/mred/wxs/wxscheme.cxx
+++ b/src/mred/wxs/wxscheme.cxx
@@ -2123,7 +2123,7 @@ void *wxSchemeYield(void *sema)
       return scheme_false;
   } else if (sema) {
     if (!scheme_is_evt((Scheme_Object *)sema))
-      scheme_wrong_type("yield", "evt or 'wait", -1, 0, (Scheme_Object **)&sema);
+      scheme_wrong_type("yield", "evt or 'wait", -1, 0, (Scheme_Object **)(void *)&sema);
 
     if (is_handler)
       return wxDispatchEventsUntilWaitable((wxDispatch_Check_Fun)NULL, NULL, (Scheme_Object *)sema);
diff --git a/src/wxxt/src/DataStructures/Object.h b/src/wxxt/src/DataStructures/Object.h
index e74d4b626f..7499438f00 100644
--- a/src/wxxt/src/DataStructures/Object.h
+++ b/src/wxxt/src/DataStructures/Object.h
@@ -37,28 +37,28 @@
 //-----------------------------------------------------------------------------
 
 #ifdef MZ_PRECISE_GC
-# define WXGC_IGNORE(base, ptr) GC_finalization_weak_ptr((void **)base, (void **)&(ptr) - (void **)base)
+# define WXGC_IGNORE(base, ptr) GC_finalization_weak_ptr((void **)(void *)base, (void **)(void *)&(ptr) - (void **)(void *)base)
 # define COPYSTRING_TO_ALIGNED(s, d) copystring_to_aligned(s, d)
 # define DELETE_OBJ delete_wxobject
 # define DELETE_VAL delete
 # define MALLOC_SAFEREF() (void *)GC_malloc_immobile_box(GC_malloc_weak_box(NULL, NULL, 0))
-# define FREE_SAFEREF(x) GC_free_immobile_box((void **)x)
+# define FREE_SAFEREF(x) GC_free_immobile_box((void **)(void *)x)
 typedef struct {
   short tag;
   short filler_used_for_hashing;
   void *val;
 } wxWeak_Box;
 # define SET_SAFEREF(x, v) (*(wxWeak_Box **)x)->val = gcOBJ_TO_PTR(v)
-# define GET_SAFEREF(x) ((*(void **)x) ? gcPTR_TO_OBJ((*(wxWeak_Box **)x)->val) : NULL)
+# define GET_SAFEREF(x) ((*(void **)(void *)x) ? gcPTR_TO_OBJ((*(wxWeak_Box **)(void *)x)->val) : NULL)
 #else
-# define WXGC_IGNORE(base, ptr) GC_general_register_disappearing_link((void **)&(ptr), NULL)
+# define WXGC_IGNORE(base, ptr) GC_general_register_disappearing_link((void **)(void *)&(ptr), NULL)
 # define COPYSTRING_TO_ALIGNED(s, d) (s + d)
 # define DELETE_OBJ delete
 # define DELETE_VAL delete
 # define MALLOC_SAFEREF() malloc(sizeof(void *))
 # define FREE_SAFEREF(x) free(x)
-# define SET_SAFEREF(x, v) (*(void **)x) = v
-# define GET_SAFEREF(x) (*(void **)x)
+# define SET_SAFEREF(x, v) (*(void **)(void *)x) = v
+# define GET_SAFEREF(x) (*(void **)(void *)x)
 #endif
 #define WXGC_NO_CLEANUP FALSE
 
diff --git a/src/wxxt/src/Windows/Canvas.cc b/src/wxxt/src/Windows/Canvas.cc
index c83a72032b..7c355d8264 100644
--- a/src/wxxt/src/Windows/Canvas.cc
+++ b/src/wxxt/src/Windows/Canvas.cc
@@ -348,11 +348,11 @@ void wxCanvas::SetScrollbars(int h_pixels, int v_pixels, int x_len, int y_len,
       a[0].name = XtNabs_height;
       a[0].value = v_pixels > 0 ? ((Dimension)v_size) : 0;
       a[1].name = XtNrel_height;
-      *(float *)&(a[1].value) = (float)(v_pixels > 0 ? 0.0 : 1.0);
+      *(float *)(void *)&(a[1].value) = (float)(v_pixels > 0 ? 0.0 : 1.0);
       a[2].name = XtNabs_width;
       a[2].value = h_pixels > 0 ? ((Dimension)h_size) : 0;
       a[3].name = XtNrel_width;
-      *(float *)&(a[3].value) = (float)(h_pixels > 0 ? 0.0 : 1.0);
+      *(float *)(void *)&(a[3].value) = (float)(h_pixels > 0 ? 0.0 : 1.0);
 
       XtSetValues(X->handle, a, 4);
 
@@ -372,19 +372,19 @@ void wxCanvas::SetScrollbars(int h_pixels, int v_pixels, int x_len, int y_len,
       a[0].name = XtNabs_height;
       a[0].value = 0;
       a[1].name = XtNrel_height;
-      *(float *)&(a[1].value) = 1.0;
+      *(float *)(void *)&(a[1].value) = 1.0;
       a[2].name = XtNabs_width;
       a[2].value = 0;
       a[3].name = XtNrel_width;
-      *(float *)&(a[3].value) = 1.0;
+      *(float *)(void *)&(a[3].value) = 1.0;
       a[4].name = XtNabs_x;
       a[4].value = 0;
       a[5].name = XtNabs_y;
       a[5].value = 0;
       a[6].name = XtNrel_x;
-      *(float *)&(a[6].value) = 0.0;
+      *(float *)(void *)&(a[6].value) = 0.0;
       a[7].name = XtNrel_y;
-      *(float *)&(a[7].value) = 0.0;
+      *(float *)(void *)&(a[7].value) = 0.0;
 
       XtSetValues(X->handle, a, 8);