diff --git a/ipcalc.spec b/ipcalc.spec
index f4bffe7..864ecea 100644
--- a/ipcalc.spec
+++ b/ipcalc.spec
@@ -15,6 +15,8 @@ BuildRequires: GeoIP-devel
 BuildRequires: popt-devel
 # Explicitly conflict with older initscript packages that ship ipcalc
 Conflicts: initscripts < 9.63
+# Obsolete ipcalculator
+Obsoletes: ipcalculator < 0.41-20
 
 %description
 ipcalc provides a simple way to calculate IP information for a host.