diff --git a/Source/am_map.c b/Source/am_map.c
index c5331859..7b51c406 100644
--- a/Source/am_map.c
+++ b/Source/am_map.c
@@ -779,8 +779,8 @@ boolean AM_Responder
       if (ev->type == ev_mouseb_down &&
       	(ev->data1 == MOUSE_BUTTON_WHEELUP || ev->data1 == MOUSE_BUTTON_WHEELDOWN))
       {
-        mtof_zoommul = M2_ZOOMIN;
-        ftom_zoommul = M2_ZOOMOUT;
+        mtof_zoommul = M2_ZOOMOUT;
+        ftom_zoommul = M2_ZOOMIN;
       }
       else
       {
@@ -793,8 +793,8 @@ boolean AM_Responder
       if (ev->type == ev_mouseb_down &&
       	(ev->data1 == MOUSE_BUTTON_WHEELUP || ev->data1 == MOUSE_BUTTON_WHEELDOWN))
       {
-        mtof_zoommul = M2_ZOOMOUT;
-        ftom_zoommul = M2_ZOOMIN;
+        mtof_zoommul = M2_ZOOMIN;
+        ftom_zoommul = M2_ZOOMOUT;
       }
       else
       {
diff --git a/Source/m_misc.c b/Source/m_misc.c
index d3d6c2af..506ed776 100644
--- a/Source/m_misc.c
+++ b/Source/m_misc.c
@@ -1154,7 +1154,7 @@ default_t defaults[] = {
     {0}, {UL,UL}, input, ss_keys, wad_no,
     "key to enlarge automap",
     input_map_zoomin, { {input_type_key, '='},
-                        {input_type_mouseb, MOUSE_BUTTON_WHEELDOWN} }
+                        {input_type_mouseb, MOUSE_BUTTON_WHEELUP} }
   },
 
   {
@@ -1163,7 +1163,7 @@ default_t defaults[] = {
     {0}, {UL,UL}, input, ss_keys, wad_no,
     "key to reduce automap",
     input_map_zoomout, { {input_type_key, '-'},
-                         {input_type_mouseb, MOUSE_BUTTON_WHEELUP} }
+                         {input_type_mouseb, MOUSE_BUTTON_WHEELDOWN} }
   },
 
   {