diff --git a/benchs/dune b/benchs/dune
index ff3ac80f..c8430fc7 100644
--- a/benchs/dune
+++ b/benchs/dune
@@ -4,5 +4,6 @@
              containers-thread benchmark gen iter qcheck oseq
              batteries base sek)
   (flags :standard -warn-error -3-5 -safe-string -color always -open CCShims_)
+  (optional)
   (ocamlopt_flags :standard -O3 -color always
                    -unbox-closures -unbox-closures-factor 20))
diff --git a/containers-data.opam b/containers-data.opam
index 202f4899..c30d80d4 100644
--- a/containers-data.opam
+++ b/containers-data.opam
@@ -11,7 +11,7 @@ build: [
 ]
 depends: [
   "ocaml" { >= "4.03.0" }
-  "dune" { >= "1.4" }
+  "dune" { >= "2.0" }
   "containers" { = version }
   "seq"
   "qtest" { with-test }
diff --git a/containers-thread.opam b/containers-thread.opam
index d4c32535..6af5aaf7 100644
--- a/containers-thread.opam
+++ b/containers-thread.opam
@@ -11,7 +11,7 @@ build: [
 ]
 depends: [
   "ocaml" { >= "4.03.0" }
-  "dune" { >= "1.4" }
+  "dune" { >= "2.0" }
   "base-threads"
   "dune-configurator"
   "containers" { = version }
diff --git a/containers.opam b/containers.opam
index 4330b193..59be282c 100644
--- a/containers.opam
+++ b/containers.opam
@@ -12,7 +12,7 @@ build: [
 ]
 depends: [
   "ocaml" { >= "4.03.0" }
-  "dune" { >= "1.4" }
+  "dune" { >= "2.0" }
   "dune-configurator"
   "seq" # compat
   "either" # compat
diff --git a/dune b/dune
index f8d56234..ba269461 100644
--- a/dune
+++ b/dune
@@ -3,7 +3,7 @@
  (deps (package containers-data) ./src/mdx_runner.exe)
  (action (run ./src/mdx_runner.exe)))
 
-(alias
- (name runtest)
+(rule
+ (alias runtest)
  (package containers-data)
  (action (diff README.md README.md.corrected)))
diff --git a/dune-project b/dune-project
index f9337290..929c696e 100644
--- a/dune-project
+++ b/dune-project
@@ -1 +1 @@
-(lang dune 1.4)
+(lang dune 2.0)
diff --git a/examples/dune b/examples/dune
index 13b6e613..e8ed9dc0 100644
--- a/examples/dune
+++ b/examples/dune
@@ -4,16 +4,16 @@
   (libraries containers)
   (flags :standard -warn-error -a+8))
 
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (deps (source_tree test_data))
   (action
     (ignore-stdout
       (run ./id_sexp.exe test_data/benchpress.sexp))))
 
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (deps (source_tree test_data))
   (action
@@ -30,8 +30,8 @@
   (enabled_if (< %{ocaml_version} "4.08"))
   (action (with-stdout-to %{targets} (run echo "let() = print_endline {|ok|}"))))
 
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (deps (source_tree test_data))
   (enabled_if (>= %{ocaml_version} "4.08"))
diff --git a/fuzz/dune b/fuzz/dune
index 5f57001d..11342443 100644
--- a/fuzz/dune
+++ b/fuzz/dune
@@ -3,4 +3,5 @@
  (names     ccsexp_parse_string_does_not_crash
             ccutf8_string_uchar_to_bytes_is_same_as_simple_version
             ccsexp_csexp_reparse)
+ (optional)
  (libraries crowbar containers))
diff --git a/qtest/dune b/qtest/dune
index 5775f212..f55c6a09 100644
--- a/qtest/dune
+++ b/qtest/dune
@@ -6,8 +6,8 @@
 
 (rule
   (targets run_qtest.ml)
-  (deps make.bc (source_tree ../src))
-  (action (run ./make.bc -target %{targets} ../src/core ../src/unix/)))
+  (deps ./make.exe (source_tree ../src))
+  (action (run ./make.exe -target %{targets} ../src/core ../src/unix/)))
 
 (executable
   (name run_qtest)
@@ -17,16 +17,16 @@
   (flags :standard -warn-error -a -w -3-33-35-27-39-50)
   (libraries iter gen qcheck containers containers.unix unix uutf threads))
 
-(alias
-  (name    runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (package containers)
   (action  (run ./run_qtest.exe)))
 
 (rule
   (targets run_qtest_data.ml)
-  (deps make.bc (source_tree ../src/data))
-  (action (run ./make.bc -target %{targets} ../src/data)))
+  (deps make.exe (source_tree ../src/data))
+  (action (run ./make.exe -target %{targets} ../src/data)))
 
 (executable
   (name run_qtest_data)
@@ -36,16 +36,16 @@
   (flags :standard -warn-error -a -w -3-33-35-27-39-50)
   (libraries iter gen qcheck containers containers-data))
 
-(alias
-  (name    runtest)
+(rule
+  (alias runtest)
   (package containers-data)
   (locks /ctest)
   (action  (run ./run_qtest_data.exe)))
 
 (rule
   (targets run_qtest_thread.ml)
-  (deps make.bc (source_tree ../src/threads))
-  (action (run ./make.bc -target %{targets} ../src/threads)))
+  (deps make.exe (source_tree ../src/threads))
+  (action (run ./make.exe -target %{targets} ../src/threads)))
 
 (executable
   (name run_qtest_thread)
@@ -55,8 +55,8 @@
   (flags :standard -warn-error -a -w -3-33-35-27-39-50)
   (libraries qcheck containers containers-thread iter threads))
 
-(alias
-  (name    runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (package containers-thread)
   (action  (run ./run_qtest_thread.exe)))
diff --git a/src/codegen/tests/dune b/src/codegen/tests/dune
index 320af55e..4aeb4c37 100644
--- a/src/codegen/tests/dune
+++ b/src/codegen/tests/dune
@@ -19,6 +19,6 @@
   (flags :standard -warn-error -a+8)
   (libraries containers))
 
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (action (run ./test_bitfield.exe)))
diff --git a/src/core/tests/dune b/src/core/tests/dune
index 03ca9a0d..7a26dadc 100644
--- a/src/core/tests/dune
+++ b/src/core/tests/dune
@@ -24,21 +24,21 @@
   (modules test_csexp)
   (libraries containers csexp qcheck-core qcheck))
 
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (package containers)
   (action (run ./test_random.exe)))
 
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (package containers)
   (action (run ./test_csexp.exe)))
 
 ; what matters is that it compiles
-(alias
-  (name runtest)
+(rule
+  (alias runtest)
   (locks /ctest)
   (package containers)
   (action  (run ./check_labelled_mods.exe)))