diff --git a/pkgs/applications/graphics/dia/default.nix b/pkgs/applications/graphics/dia/default.nix
index 6b75bf11d423..0adc585603ef 100644
--- a/pkgs/applications/graphics/dia/default.nix
+++ b/pkgs/applications/graphics/dia/default.nix
@@ -34,6 +34,9 @@ stdenv.mkDerivation {
 
   patches = [ ./poppler-22_09-build-fix.patch ];
 
+  # Required for the PDF plugin when building with clang.
+  CXXFLAGS = "-std=c++17";
+
   preConfigure = ''
     patchShebangs .
   '';