diff --git a/plasma/framesvg.cpp b/plasma/framesvg.cpp
index 8def278d..e5389d95 100644
--- a/plasma/framesvg.cpp
+++ b/plasma/framesvg.cpp
@@ -303,7 +303,7 @@ bool FrameSvg::hasElementPrefix(Plasma::Location location) const
     }
 }
 
-QString FrameSvg::prefix()
+QString FrameSvg::prefix() const
 {
     if (d->prefix.isEmpty()) {
         return d->prefix;
diff --git a/plasma/framesvg.h b/plasma/framesvg.h
index 050c2d0f..9cc446f6 100644
--- a/plasma/framesvg.h
+++ b/plasma/framesvg.h
@@ -207,7 +207,7 @@ class PLASMA_EXPORT FrameSvg : public Svg
          * Returns the prefix for SVG elements of the FrameSvg
          * @return the prefix
          */
-        Q_INVOKABLE QString prefix();
+        Q_INVOKABLE QString prefix() const;
 
         /**
          * Returns a mask that tightly contains the fully opaque areas of the svg