diff --git a/.travis.yml b/.travis.yml
index 7342796..6205c56 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,12 +21,8 @@ before_install:
   - yes | sudo add-apt-repository ppa:cmrx64/cargo
   - sudo apt-get update
 install:
-  # cargo
-  - sudo apt-get install cargo
-  # rustc
-  - curl http://static.rust-lang.org/cargo-dist/cargo-nightly-linux.tar.gz |
-    sudo tar --strip-components 1 -C /usr -xzf -
-  - curl http://www.rust-lang.org/rustup.sh | sudo sh -
+  - wget http://www.rust-lang.org/rustup.sh
+  - sudo sh ./rustup.sh
   - rustc -v
 script:
   - cargo build
@@ -36,4 +32,6 @@ script:
   - make clean
   - make doc
 after_script:
-  - curl http://www.rust-ci.org/artifacts/put?t=$RUSTCI_TOKEN | sh
+  - wget -O after_script.sh http://www.rust-ci.org/artifacts/put?t=$RUSTCI_TOKEN
+  - chmod +x after_script.sh
+  - sh ./after_script.sh
diff --git a/src/projection.rs b/src/projection.rs
index 7f05663..9ed41c0 100644
--- a/src/projection.rs
+++ b/src/projection.rs
@@ -159,9 +159,9 @@ impl<S: BaseFloat> Projection<S> for Perspective<S> {
 
 impl<S: BaseFloat> ToMatrix4<S> for Perspective<S> {
     fn to_matrix4(&self) -> Matrix4<S> {
-        assert!(self.left   > self.right, "`left` cannot be greater than `right`, found: left: {} right: {}", self.left, self.right);
-        assert!(self.bottom > self.top,   "`bottom` cannot be greater than `top`, found: bottom: {} top: {}", self.bottom, self.top);
-        assert!(self.near   > self.far,   "`near` cannot be greater than `far`, found: near: {} far: {}", self.near, self.far);
+        assert!(self.left   <= self.right, "`left` cannot be greater than `right`, found: left: {} right: {}", self.left, self.right);
+        assert!(self.bottom <= self.top,   "`bottom` cannot be greater than `top`, found: bottom: {} top: {}", self.bottom, self.top);
+        assert!(self.near   <= self.far,   "`near` cannot be greater than `far`, found: near: {} far: {}", self.near, self.far);
 
         let two: S = cast(2i).unwrap();