diff --git a/.circleci/config.yml b/.circleci/config.yml
index 26ca00051..c1929f30f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -19,9 +19,9 @@ jobs:
           name: Install lint deps
           command: |
             git config --global --unset url."ssh://git@github.com".insteadOf || true
-            rustup toolchain install nightly
+            rustup toolchain install nightly-2019-02-27
             rustup component add rustfmt
-            rustup component add clippy --toolchain=nightly || cargo +nightly install --git https://github.com/rust-lang/rust-clippy/ --force clippy
+            rustup component add clippy --toolchain=nightly-2019-02-27 || cargo +nightly-2019-02-27 install --git https://github.com/rust-lang/rust-clippy/ --force clippy
       - run:
           name: Execute lints
           command: |
@@ -272,7 +272,7 @@ jobs:
             sudo apt-get install -y cmake
             curl -O https://releases.llvm.org/7.0.0/clang+llvm-7.0.0-x86_64-linux-gnu-ubuntu-16.04.tar.xz
             tar xf clang+llvm-7.0.0-x86_64-linux-gnu-ubuntu-16.04.tar.xz
-      - run: rustup default nightly
+      - run: rustup default nightly-2019-02-27
       - run: |
           export LLVM_SYS_70_PREFIX="`pwd`/clang+llvm-7.0.0-x86_64-linux-gnu-ubuntu-16.04/"
           make test
diff --git a/Makefile b/Makefile
index c869155b8..19ce942d1 100644
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,7 @@ integration-tests: release
 
 lint:
 	cargo fmt --all -- --check
-	cargo +nightly clippy --all
+	cargo +nightly-2019-02-27 clippy --all
 
 precommit: lint test
 
diff --git a/lib/emscripten/src/syscalls/mod.rs b/lib/emscripten/src/syscalls/mod.rs
index 16f9c4df4..de02b998d 100644
--- a/lib/emscripten/src/syscalls/mod.rs
+++ b/lib/emscripten/src/syscalls/mod.rs
@@ -266,7 +266,7 @@ pub fn ___syscall140(ctx: &mut Ctx, _which: i32, mut varargs: VarArgs) -> i32 {
     let ret = unsafe { lseek(fd, offset, whence) as i32 };
     #[allow(clippy::cast_ptr_alignment)]
     let result_ptr = emscripten_memory_pointer!(ctx.memory(0), result_ptr_value) as *mut i32;
-    assert_eq!(4, mem::align_of_val(&result_ptr));
+    assert_eq!(8, mem::align_of_val(&result_ptr));
     unsafe {
         *result_ptr = ret;
     }