diff --git a/Cargo.lock b/Cargo.lock
index e244f82..2a1abd3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -17,7 +17,7 @@ version = "0.24.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "shared_library 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -26,7 +26,7 @@ name = "atty"
 version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -38,7 +38,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "backtrace-sys 0.1.23 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-demangle 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -49,7 +49,7 @@ version = "0.1.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -83,7 +83,7 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "gleam 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -94,7 +94,7 @@ dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "block 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-graphics 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "objc 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -106,7 +106,7 @@ dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "block 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-graphics 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "objc 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -116,7 +116,7 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "core-foundation-sys 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -125,7 +125,7 @@ version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "core-foundation-sys 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -133,7 +133,7 @@ name = "core-foundation-sys"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -149,7 +149,7 @@ dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-foundation 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -160,7 +160,7 @@ dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-foundation 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -252,7 +252,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "gfx-backend-dx12"
 version = "0.1.0"
-source = "git+https://github.com/gfx-rs/gfx#25c2517efc83aa85e58dbce2ce95107905787cf1"
+source = "git+https://github.com/gfx-rs/gfx#91ec6303fded63498b01e4a55e8ebe6768d3c2cc"
 dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "derivative 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -268,13 +268,14 @@ dependencies = [
 [[package]]
 name = "gfx-backend-metal"
 version = "0.1.0"
-source = "git+https://github.com/gfx-rs/gfx#25c2517efc83aa85e58dbce2ce95107905787cf1"
+source = "git+https://github.com/gfx-rs/gfx#91ec6303fded63498b01e4a55e8ebe6768d3c2cc"
 dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "block 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "cocoa 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-foundation 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-graphics 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "derivative 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "gfx-hal 0.1.0 (git+https://github.com/gfx-rs/gfx)",
  "io-surface 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -289,7 +290,7 @@ dependencies = [
 [[package]]
 name = "gfx-backend-vulkan"
 version = "0.1.0"
-source = "git+https://github.com/gfx-rs/gfx#25c2517efc83aa85e58dbce2ce95107905787cf1"
+source = "git+https://github.com/gfx-rs/gfx#91ec6303fded63498b01e4a55e8ebe6768d3c2cc"
 dependencies = [
  "ash 0.24.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -307,7 +308,7 @@ dependencies = [
 [[package]]
 name = "gfx-hal"
 version = "0.1.0"
-source = "git+https://github.com/gfx-rs/gfx#25c2517efc83aa85e58dbce2ce95107905787cf1"
+source = "git+https://github.com/gfx-rs/gfx#91ec6303fded63498b01e4a55e8ebe6768d3c2cc"
 dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -352,7 +353,7 @@ dependencies = [
  "core-graphics 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "gl_generator 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "objc 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "osmesa-sys 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "shared_library 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -379,7 +380,7 @@ dependencies = [
  "core-foundation 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "gleam 0.4.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "leaky-cow 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -420,7 +421,7 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.41"
+version = "0.2.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -445,7 +446,7 @@ name = "malloc_buf"
 version = "0.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -453,7 +454,7 @@ name = "memchr"
 version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -461,7 +462,7 @@ name = "memmap"
 version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -474,7 +475,7 @@ dependencies = [
  "block 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "cocoa 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "objc 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "objc-foundation 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -578,7 +579,7 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -647,7 +648,7 @@ version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -712,7 +713,7 @@ name = "tempfile"
 version = "3.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -732,7 +733,7 @@ name = "termion"
 version = "1.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -785,7 +786,7 @@ version = "0.12.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "token_store 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "wayland-scanner 0.12.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "wayland-sys 0.12.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -879,7 +880,7 @@ dependencies = [
  "core-foundation 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-graphics 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "objc 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "percent-encoding 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "wayland-client 0.12.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -903,7 +904,7 @@ name = "x11"
 version = "2.17.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -913,7 +914,7 @@ version = "2.17.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -922,7 +923,7 @@ name = "xcb"
 version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -982,7 +983,7 @@ dependencies = [
 "checksum lazy_static 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e6412c5e2ad9584b0b8e979393122026cdd6d2a80b933f890dcd694ddbe73739"
 "checksum leak 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "bd100e01f1154f2908dfa7d02219aeab25d0b9c7fa955164192e3245255a0c73"
 "checksum leaky-cow 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "40a8225d44241fd324a8af2806ba635fc7c8a7e9a7de4d5cf3ef54e71f5926fc"
-"checksum libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)" = "ac8ebf8343a981e2fa97042b14768f02ed3e1d602eac06cae6166df3c8ced206"
+"checksum libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)" = "b685088df2b950fccadf07a7187c8ef846a959c142338a48f9dc0b94517eb5f1"
 "checksum libloading 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9c3ad660d7cb8c5822cd83d10897b0f1f1526792737a179e73896152f85b88c2"
 "checksum log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "89f010e843f2b1a31dbd316b3b8d443758bc634bed37aabade59c686d644e0a2"
 "checksum malloc_buf 0.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "62bb907fe88d54d8d9ce32a3cceab4218ed2f6b7d35617cafe9adf84e43919cb"
diff --git a/libportability-gfx/src/impls.rs b/libportability-gfx/src/impls.rs
index 00fd0c6..3787a23 100644
--- a/libportability-gfx/src/impls.rs
+++ b/libportability-gfx/src/impls.rs
@@ -2186,12 +2186,22 @@ pub extern "C" fn gfxAllocateDescriptorSets(
 #[inline]
 pub extern "C" fn gfxFreeDescriptorSets(
     _device: VkDevice,
-    _descriptorPool: VkDescriptorPool,
-    _descriptorSetCount: u32,
-    _pDescriptorSets: *const VkDescriptorSet,
+    mut descriptorPool: VkDescriptorPool,
+    descriptorSetCount: u32,
+    pDescriptorSets: *const VkDescriptorSet,
 ) -> VkResult {
-    error!("gfxFreeDescriptorSets not implemented");
-    VkResult::VK_NOT_READY
+    let descriptor_sets = unsafe {
+        slice::from_raw_parts(pDescriptorSets, descriptorSetCount as _)
+    };
+
+    descriptorPool.free_sets(
+        &descriptor_sets
+            .into_iter()
+            .filter_map(|set| set.unbox())
+            .collect::<Vec<_>>()
+    );
+
+    VkResult::VK_SUCCESS
 }
 #[inline]
 pub extern "C" fn gfxUpdateDescriptorSets(