diff --git a/src/qml/Chat/Timeline/EventImage.qml b/src/qml/Chat/Timeline/EventImage.qml
index e1270327..78183f35 100644
--- a/src/qml/Chat/Timeline/EventImage.qml
+++ b/src/qml/Chat/Timeline/EventImage.qml
@@ -24,10 +24,13 @@ HMxcImage {
     readonly property bool isEncrypted: ! Utils.isEmptyObject(cryptDict)
     readonly property string openUrl: isEncrypted ? cachedPath : image.httpUrl
 
+    readonly property real maxHeight:
+        theme.chat.message.thumbnailMaxHeightRatio
+
     readonly property size fitSize: Utils.fitSize(
         // Minimum display size
-        192,
-        192,
+        theme.chat.message.thumbnailMinSize.width,
+        theme.chat.message.thumbnailMinSize.height,
 
         // Real size
         loader.singleMediaInfo.thumbnail_width ||
@@ -41,8 +44,8 @@ HMxcImage {
         600,
 
         // Maximum display size
-        Math.min(eventList.height / 3, eventContent.messageBodyWidth),
-        eventList.height / 3,
+        Math.min(eventList.height * maxHeight, eventContent.messageBodyWidth),
+        eventList.height * maxHeight,
     )
 
 
diff --git a/src/themes/Default.qpl b/src/themes/Default.qpl
index f6801c23..52faf6f2 100644
--- a/src/themes/Default.qpl
+++ b/src/themes/Default.qpl
@@ -352,11 +352,16 @@ chat:
         string styleInclude:
             '<style type"text/css">\n' + styleSheet + '\n</style>\n'
 
-        // TODO rename
+        // Prefered minimum width of file messages
         int fileMinWidth: 256
-        int thumbnailWidth: 256
-        int videoWidth: 640
-        int audioWidth: 320
+
+        // Don't scale down thumbnails below this size in pixels, if
+        // the becomes too small to show it at normal size.
+        size thumbnailMinSize: Qt.size(192, 192)
+
+        // How much of the chat height thumbnails can take at most,
+        // by default 0.3 for 30%.
+        real thumbnailMaxHeightRatio: 0.3
 
     daybreak:
         color background: colors.strongBackground