diff --git a/rtgui/cropwindow.cc b/rtgui/cropwindow.cc
index 2b20de001..08ea9d0f7 100644
--- a/rtgui/cropwindow.cc
+++ b/rtgui/cropwindow.cc
@@ -289,7 +289,7 @@ void CropWindow::scroll (int state, GdkScrollDirection direction, int x, int y)
 
         if (direction == GDK_SCROLL_UP && !isMaxZoom()) {
             zoomIn (true, newCenterX, newCenterY);
-        } else if (!isMinZoom()) {
+        } else if (direction == GDK_SCROLL_DOWN && !isMinZoom()) {
             zoomOut (true, newCenterX, newCenterY);
         }
     }
diff --git a/rtgui/thumbbrowserbase.cc b/rtgui/thumbbrowserbase.cc
index abb8ec68d..2d27550bc 100644
--- a/rtgui/thumbbrowserbase.cc
+++ b/rtgui/thumbbrowserbase.cc
@@ -71,20 +71,24 @@ void ThumbBrowserBase::scrollChanged ()
 void ThumbBrowserBase::scroll (int direction)
 {
     // GUI already acquired when here
-    if (arrangement == TB_Vertical) {
-        vscroll.set_value (vscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * vscroll.get_adjustment()->get_step_increment());
-    } else {
-        hscroll.set_value (hscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * hscroll.get_adjustment()->get_step_increment());
+    if (direction == GDK_SCROLL_UP || direction == GDK_SCROLL_DOWN) {
+        if (arrangement == TB_Vertical) {
+            vscroll.set_value (vscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * vscroll.get_adjustment()->get_step_increment());
+        } else {
+            hscroll.set_value (hscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * hscroll.get_adjustment()->get_step_increment());
+        }
     }
 }
 
 void ThumbBrowserBase::scrollPage (int direction)
 {
     // GUI already acquired when here
-    if (arrangement == TB_Vertical) {
-        vscroll.set_value (vscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * vscroll.get_adjustment()->get_page_increment());
-    } else {
-        hscroll.set_value (hscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * hscroll.get_adjustment()->get_page_increment());
+    if (direction == GDK_SCROLL_UP || direction == GDK_SCROLL_DOWN) {
+        if (arrangement == TB_Vertical) {
+            vscroll.set_value (vscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * vscroll.get_adjustment()->get_page_increment());
+        } else {
+            hscroll.set_value (hscroll.get_value() + (direction == GDK_SCROLL_DOWN ? +1 : -1) * hscroll.get_adjustment()->get_page_increment());
+        }
     }
 }