diff --git a/kstars/fitsviewer/fitsview.cpp b/kstars/fitsviewer/fitsview.cpp
--- a/kstars/fitsviewer/fitsview.cpp
+++ b/kstars/fitsviewer/fitsview.cpp
@@ -32,7 +32,7 @@
 #define BASE_OFFSET    50
 #define ZOOM_DEFAULT   100.0
 #define ZOOM_MIN       10
-#define ZOOM_MAX       400
+#define ZOOM_MAX       150
 #define ZOOM_LOW_INCR  10
 #define ZOOM_HIGH_INCR 50
 
@@ -532,6 +532,7 @@
     {
         currentZoom = ZOOM_MAX;
         emit actionUpdated("view_zoom_in", false);
+        return;
     }
 
     currentWidth  = image_width * (currentZoom / ZOOM_DEFAULT);