diff --git a/CHANGELOG.md b/CHANGELOG.md
index 13757dc5..e9127937 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+### Version 2.1.5
+ - Fix issue where some images will incorrectly reduce bit depth ([#140](https://github.com/shssoichiro/oxipng/issues/140))
+
 ### Version 2.1.4
  - Bump `image` crate to 0.20.0
 
diff --git a/Cargo.lock b/Cargo.lock
index 5f8e7cb0..651ea8b6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -132,7 +132,7 @@ dependencies = [
 
 [[package]]
 name = "deflate"
-version = "0.7.18"
+version = "0.7.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "adler32 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -256,7 +256,7 @@ dependencies = [
 
 [[package]]
 name = "oxipng"
-version = "2.1.4"
+version = "2.1.5"
 dependencies = [
  "bit-vec 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -278,7 +278,7 @@ version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "deflate 0.7.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "deflate 0.7.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "inflate 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-iter 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -422,7 +422,7 @@ dependencies = [
 "checksum crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f739f8c5363aca78cfb059edf753d8f0d36908c348f3d8d1503f03d8b75d9cf3"
 "checksum crossbeam-epoch 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "927121f5407de9956180ff5e936fe3cf4324279280001cd56b669d28ee7e9150"
 "checksum crossbeam-utils 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "2760899e32a1d58d5abb31129f8fae5de75220bc2176e77ff7c627ae45c918d9"
-"checksum deflate 0.7.18 (registry+https://github.com/rust-lang/crates.io-index)" = "32c8120d981901a9970a3a1c97cf8b630e0fa8c3ca31e75b6fd6fd5f9f427b31"
+"checksum deflate 0.7.19 (registry+https://github.com/rust-lang/crates.io-index)" = "8a6abb26e16e8d419b5c78662aa9f82857c2386a073da266840e474d5055ec86"
 "checksum either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3be565ca5c557d7f59e7cfcf1844f9e3033650c929c6566f511e8005f205c1d0"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 "checksum image 0.20.0 (registry+https://github.com/rust-lang/crates.io-index)" = "60710fd3cb40c2434451d8d5147bcf39bbb68aae0741041133e09439cb2401e3"
diff --git a/Cargo.toml b/Cargo.toml
index 839d5c39..b08438e3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,7 +14,7 @@ homepage = "https://github.com/shssoichiro/oxipng"
 license = "MIT"
 name = "oxipng"
 repository = "https://github.com/shssoichiro/oxipng"
-version = "2.1.4"
+version = "2.1.5"
 
 [badges]
 travis-ci = { repository = "shssoichiro/oxipng", branch = "master" }