diff --git a/profiles/package.mask b/profiles/package.mask
index 8b75fae7d34c3..aff5f4ffdb211 100644
--- a/profiles/package.mask
+++ b/profiles/package.mask
@@ -33,6 +33,11 @@
 
 #--- END OF EXAMPLES ---
 
+# Ulrich Müller <ulm@gentoo.org> (2024-02-08)
+# Masked for testing.
+# Test failure in watchpoints.dem, undefined function FresnelC.
+~sci-visualization/gnuplot-6.0.0
+
 # Michał Górny <mgorny@gentoo.org> (2024-02-07)
 # Does not build anymore.  Carries a large stack of patches already.
 # Last upstream activity in late 2020.  No reverse dependencies left.