diff --git a/pkgs/kde/plasma/plasma-workspace/default.nix b/pkgs/kde/plasma/plasma-workspace/default.nix
index 964525c99c9f..7ecc76961fd0 100644
--- a/pkgs/kde/plasma/plasma-workspace/default.nix
+++ b/pkgs/kde/plasma/plasma-workspace/default.nix
@@ -37,6 +37,9 @@ mkKdeDerivation {
       # @QtBinariesDir@ only appears in the *removed* lines of the diff
       QtBinariesDir = null;
     })
+
+    # stop accidentally duplicating fontconfig configs
+    ./fontconfig.patch
   ];
 
   outputs = [
diff --git a/pkgs/kde/plasma/plasma-workspace/fontconfig.patch b/pkgs/kde/plasma/plasma-workspace/fontconfig.patch
new file mode 100644
index 000000000000..8b6f6cfb3b0c
--- /dev/null
+++ b/pkgs/kde/plasma/plasma-workspace/fontconfig.patch
@@ -0,0 +1,15 @@
+diff --git a/kcms/fonts/kxftconfig.cpp b/kcms/fonts/kxftconfig.cpp
+index b67d885de7..d5c469687a 100644
+--- a/kcms/fonts/kxftconfig.cpp
++++ b/kcms/fonts/kxftconfig.cpp
+@@ -310,6 +310,10 @@ bool KXftConfig::apply()
+             m_excludePixelRange.from = (int)point2Pixel(m_excludeRange.from);
+             m_excludePixelRange.to = (int)point2Pixel(m_excludeRange.to);
+ 
++            // Ensure m_doc is the config file we want
++            m_doc.clear();
++            parseConfigFile(m_file);
++
+             FcAtomic *atomic = FcAtomicCreate((const unsigned char *)(QFile::encodeName(m_file).data()));
+ 
+             ok = false;