diff --git a/pkgs/development/python-modules/seqdiag/default.nix b/pkgs/development/python-modules/seqdiag/default.nix
new file mode 100644
index 00000000000..98a81873a71
--- /dev/null
+++ b/pkgs/development/python-modules/seqdiag/default.nix
@@ -0,0 +1,29 @@
+{ stdenv, fetchurl, buildPythonPackage, pep8, nose, unittest2, docutils
+, blockdiag
+}:
+
+buildPythonPackage rec {
+  name = "seqdiag-0.9.4";
+
+  src = fetchurl {
+    url = "mirror://pypi/s/seqdiag/${name}.tar.gz";
+    sha256 = "1qa7d0m1wahvmrj95rxkb6128cbwd4w3gy8gbzncls66h46bifiz";
+  };
+
+  buildInputs = [ pep8 nose unittest2 docutils ];
+
+  propagatedBuildInputs = [ blockdiag ];
+
+  # Tests fail:
+  #   ...
+  #   ERROR: Failure: OSError ([Errno 2] No such file or directory: '/tmp/nix-build-python2.7-seqdiag-0.9.0.drv-0/seqdiag-0.9.0/src/seqdiag/tests/diagrams/')
+  doCheck = false;
+
+  meta = with stdenv.lib; {
+    description = "Generate sequence-diagram image from spec-text file (similar to Graphviz)";
+    homepage = http://blockdiag.com/;
+    license = licenses.asl20;
+    platforms = platforms.linux;
+    maintainers = with maintainers; [ bjornfor ];
+  };
+}
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index d20c8fdd3ce..0be1c2e484b 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -18636,31 +18636,7 @@ in {
     };
   };
 
-  seqdiag = buildPythonPackage rec {
-    name = "seqdiag-0.9.4";
-
-    src = pkgs.fetchurl {
-      url = "mirror://pypi/s/seqdiag/${name}.tar.gz";
-      sha256 = "1qa7d0m1wahvmrj95rxkb6128cbwd4w3gy8gbzncls66h46bifiz";
-    };
-
-    buildInputs = with self; [ pep8 nose unittest2 docutils ];
-
-    propagatedBuildInputs = with self; [ blockdiag ];
-
-    # Tests fail:
-    #   ...
-    #   ERROR: Failure: OSError ([Errno 2] No such file or directory: '/tmp/nix-build-python2.7-seqdiag-0.9.0.drv-0/seqdiag-0.9.0/src/seqdiag/tests/diagrams/')
-    doCheck = false;
-
-    meta = {
-      description = "Generate sequence-diagram image from spec-text file (similar to Graphviz)";
-      homepage = http://blockdiag.com/;
-      license = licenses.asl20;
-      platforms = platforms.linux;
-      maintainers = with maintainers; [ bjornfor ];
-    };
-  };
+  seqdiag = callPackage ../development/python-modules/seqdiag { };
 
   pysendfile = buildPythonPackage rec {
     name = "pysendfile-${version}";