diff --git a/.drone.yml b/.drone.yml
index c44977b..541c8ea 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -4,19 +4,31 @@ name: default
 steps:
   - name: vet
     image: golang:1.11-stretch
+    environment:
+      DEP_VERSION: 0.5.0
     pull: always
     commands:
-      - go get gonum.org/v1/gonum/graph
+      - curl -L -s https://github.com/golang/dep/releases/download/v${DEP_VERSION}/dep-linux-amd64 -o $GOPATH/bin/dep
+      - chmod +x $GOPATH/bin/dep
+      - dep ensure
       - cd dfd && go vet
   - name: race
     image: golang:1.11-stretch
     pull: always
+    environment:
+      DEP_VERSION: 0.5.0
     commands:
-      - go get gonum.org/v1/gonum/graph
+      - curl -L -s https://github.com/golang/dep/releases/download/v${DEP_VERSION}/dep-linux-amd64 -o $GOPATH/bin/dep
+      - chmod +x $GOPATH/bin/dep
+      - dep ensure
       - cd dfd && go test -race
   - name: test
     image: golang:1.11-stretch
     pull: always
+    environment:
+      DEP_VERSION: 0.5.0
     commands:
-      - go get gonum.org/v1/gonum/graph
+      - curl -L -s https://github.com/golang/dep/releases/download/v${DEP_VERSION}/dep-linux-amd64 -o $GOPATH/bin/dep
+      - chmod +x $GOPATH/bin/dep
+      - dep ensure
       - cd dfd && go test -cover
diff --git a/.gitignore b/.gitignore
index 7b6cfbf..1463a76 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@
 dfd/dfd
 main.go
 .DS_Store
+vendor/
diff --git a/Gopkg.lock b/Gopkg.lock
new file mode 100644
index 0000000..c7a3f60
--- /dev/null
+++ b/Gopkg.lock
@@ -0,0 +1,58 @@
+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  branch = "master"
+  digest = "1:b8c4bc3a05c3f8c96f005ebb41ba31a9551eb015947cf51127b1cca896c2176d"
+  name = "gonum.org/v1/gonum"
+  packages = [
+    "blas",
+    "blas/blas64",
+    "blas/gonum",
+    "floats",
+    "graph",
+    "graph/encoding",
+    "graph/encoding/dot",
+    "graph/formats/dot",
+    "graph/formats/dot/ast",
+    "graph/formats/dot/internal/astx",
+    "graph/formats/dot/internal/errors",
+    "graph/formats/dot/internal/lexer",
+    "graph/formats/dot/internal/parser",
+    "graph/formats/dot/internal/token",
+    "graph/internal/linear",
+    "graph/internal/ordered",
+    "graph/internal/set",
+    "graph/internal/uid",
+    "graph/iterator",
+    "graph/simple",
+    "graph/topo",
+    "graph/traverse",
+    "internal/asm/c128",
+    "internal/asm/f32",
+    "internal/asm/f64",
+    "internal/math32",
+    "lapack",
+    "lapack/gonum",
+    "lapack/lapack64",
+    "mat",
+  ]
+  pruneopts = "UT"
+  revision = "572d9101fe4fdede494f26999a59d09229b7c11b"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  input-imports = [
+    "gonum.org/v1/gonum/graph",
+    "gonum.org/v1/gonum/graph/encoding",
+    "gonum.org/v1/gonum/graph/encoding/dot",
+    "gonum.org/v1/gonum/graph/formats/dot",
+    "gonum.org/v1/gonum/graph/formats/dot/ast",
+    "gonum.org/v1/gonum/graph/internal/set",
+    "gonum.org/v1/gonum/graph/iterator",
+    "gonum.org/v1/gonum/graph/simple",
+    "gonum.org/v1/gonum/graph/topo",
+  ]
+  solver-name = "gps-cdcl"
+  solver-version = 1
diff --git a/Gopkg.toml b/Gopkg.toml
new file mode 100644
index 0000000..292552d
--- /dev/null
+++ b/Gopkg.toml
@@ -0,0 +1,7 @@
+[[constraint]]
+  branch = "master"
+  name = "gonum.org/v1/gonum"
+
+[prune]
+  go-tests = true
+  unused-packages = true