diff --git a/.rustfmt.toml b/.rustfmt.toml
new file mode 100644
index 00000000..32a9786f
--- /dev/null
+++ b/.rustfmt.toml
@@ -0,0 +1 @@
+edition = "2018"
diff --git a/.travis.yml b/.travis.yml
index 9c3c0004..b18175df 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,14 +2,16 @@ language: rust
 sudo: false
 matrix:
   include:
-    - rust: 1.32.0
-    - rust: 1.34.2
+    - rust: 1.36.0
     - rust: stable
       env:
        - FEATURES='serde-1'
     - rust: stable
       env:
        - FEATURES='rayon'
+    - rust: stable
+      env:
+       - FEATURES='std'
     - rust: beta
     - rust: nightly
       env:
@@ -41,7 +43,7 @@ script:
       cargo build --verbose --features "$FEATURES" &&
       if [ -z "$SKIP_TEST" ]; then
         cargo test --verbose --features "$FEATURES" &&
-        cargo test --release --verbose --features "$FEATURES"
+        cargo test --release --verbose --features "$FEATURES" &&
         if [ "$FEATURES" = "serde-1" ]; then
           cargo test --verbose -p test-serde &&
           cargo test --release --verbose -p test-serde
diff --git a/Cargo.toml b/Cargo.toml
index 5823a0f4..58a17304 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "indexmap"
 edition = "2018"
-version = "1.5.1"
+version = "1.6.0"
 authors = [
 "bluss",
 "Josh Stone <cuviper@gmail.com>"
@@ -37,7 +37,7 @@ serde = { version = "1.0", optional = true, default-features = false }
 rayon = { version = "1.0", optional = true }
 
 [dependencies.hashbrown]
-version = "0.8.1"
+version = "0.9.0"
 default-features = false
 features = ["raw"]
 
@@ -53,6 +53,9 @@ fxhash = "0.2.1"
 # Serialization with serde 1.0
 serde-1 = ["serde"]
 
+# Force the use of `std`, bypassing target detection.
+std = []
+
 # for testing only, of course
 test_low_transition_point = []
 test_debug = []
diff --git a/README.rst b/README.rst
index 5fbab927..2c489850 100644
--- a/README.rst
+++ b/README.rst
@@ -66,6 +66,20 @@ which is roughly:
 Recent Changes
 ==============
 
+- 1.6.0
+
+  - **MSRV**: Rust 1.36 or later is now required.
+
+  - The ``hashbrown`` dependency has been updated to version 0.9.
+
+- 1.5.2
+
+  - The new "std" feature will force the use of ``std`` for users that explicitly
+    want the default ``S = RandomState``, bypassing the autodetection added in 1.3.0,
+    by @cuviper in PR 145_.
+
+.. _145: https://github.com/bluss/indexmap/pull/145
+
 - 1.5.1
 
   - Values can now be indexed by their ``usize`` position by @cuviper in PR 132_.
diff --git a/build.rs b/build.rs
index 645c0f1c..9f9fa054 100644
--- a/build.rs
+++ b/build.rs
@@ -1,5 +1,8 @@
 fn main() {
-    let ac = autocfg::new();
-    ac.emit_sysroot_crate("std");
+    // If "std" is explicitly requested, don't bother probing the target for it.
+    match std::env::var_os("CARGO_FEATURE_STD") {
+        Some(_) => autocfg::emit("has_std"),
+        None => autocfg::new().emit_sysroot_crate("std"),
+    }
     autocfg::rerun_path("build.rs");
 }