diff --git a/pkgs/tools/misc/rrdtool/default.nix b/pkgs/tools/misc/rrdtool/default.nix
index 6d961c69b13..ee5c37ef6bb 100644
--- a/pkgs/tools/misc/rrdtool/default.nix
+++ b/pkgs/tools/misc/rrdtool/default.nix
@@ -1,4 +1,4 @@
-{ fetchurl, stdenv, gettext, perl, pkgconfig, libxml2, pango, cairo, groff
+{ fetchurl, fetchpatch, stdenv, gettext, perl, pkgconfig, libxml2, pango, cairo, groff
 , tcl-8_5, darwin }:
 
 stdenv.mkDerivation rec {
@@ -9,6 +9,14 @@ stdenv.mkDerivation rec {
     sha256 = "0ssjqpa0dwwzbylc0drmlbq922qcw8crffc0rpr805xr6n4k8zgr";
   };
 
+  patches = [
+    # fix regression https://github.com/oetiker/rrdtool-1.x/issues/794
+    (fetchpatch {
+      url = "https://github.com/oetiker/rrdtool-1.x/compare/0f28f99...f1edd12.patch";
+      sha256 = "10g56zy0rdjpv3kvvmf6vvaysmla05wi8byy3l0xrz2x8m02ylqq";
+    })
+  ];
+
   nativeBuildInputs = [ pkgconfig ];
 
   buildInputs = [ gettext perl libxml2 pango cairo groff ]