diff --git a/.travis.yml b/.travis.yml
index c8d82ad7..88f0886a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,5 +3,5 @@ language: rust
 script:
     - rustc --version
     - cargo --version
-    - cargo build --verbose
+    - cargo build --verbose --features "arbitrary generic_sizes"
     - cargo test --verbose --features arbitrary
diff --git a/Makefile b/Makefile
index 31318000..87cc39fb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,16 +1,19 @@
 tmp=_git_distcheck
 
 all:
-	cargo build --release --features arbitrary
+	cargo build --release --features "arbitrary generic_sizes"
 
 test:
-	cargo test
+	cargo test --features "arbitrary generic_sizes"
+
 
 bench:
-	cargo bench
+	cargo bench --features "arbitrary generic_sizes"
+
 
 doc:
-	cargo doc --no-deps
+	cargo doc --no-deps --features "arbitrary generic_sizes"
+
 
 clean:
 	cargo clean
diff --git a/src/structs/vectorn.rs b/src/structs/vectorn.rs
index 7b7e073b..9b0fec3e 100644
--- a/src/structs/vectorn.rs
+++ b/src/structs/vectorn.rs
@@ -120,4 +120,5 @@ impl<N: Arbitrary + Zero + Copy, D: 'static + ArrayLength<N>> Arbitrary for Vect
     }
 }
 
+
 vecn_dvec_common_impl!(VectorN, D);
diff --git a/src/structs/vectorn_macros.rs b/src/structs/vectorn_macros.rs
index ce202bb3..04b2b79a 100644
--- a/src/structs/vectorn_macros.rs
+++ b/src/structs/vectorn_macros.rs
@@ -163,7 +163,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> MulAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> MulAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
             where N: Copy + MulAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn mul_assign(&mut self, right: $vecn<N $(, $param)*>) {
@@ -175,7 +175,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> MulAssign<N> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> MulAssign<N> for $vecn<N $(, $param)*>
             where N: Copy + MulAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn mul_assign(&mut self, right: N) {
@@ -185,7 +185,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<$($param : ArrayLength<N>),*> Mul<$vecn<f32 $(, $param)*>> for f32 {
+        impl<$($param : ArrayLength<f32>),*> Mul<$vecn<f32 $(, $param)*>> for f32 {
             type Output = $vecn<f32 $(, $param)*>;
 
             #[inline]
@@ -200,7 +200,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<$($param : ArrayLength<N>),*> Mul<$vecn<f64 $(, $param)*>> for f64 {
+        impl<$($param : ArrayLength<f64>),*> Mul<$vecn<f64 $(, $param)*>> for f64 {
             type Output = $vecn<f64 $(, $param)*>;
 
             #[inline]
@@ -253,7 +253,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> DivAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> DivAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
             where N: Copy + DivAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn div_assign(&mut self, right: $vecn<N $(, $param)*>) {
@@ -265,7 +265,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> DivAssign<N> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> DivAssign<N> for $vecn<N $(, $param)*>
             where N: Copy + DivAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn div_assign(&mut self, right: N) {
@@ -313,7 +313,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> AddAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> AddAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
             where N: Copy + AddAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn add_assign(&mut self, right: $vecn<N $(, $param)*>) {
@@ -325,7 +325,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> AddAssign<N> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> AddAssign<N> for $vecn<N $(, $param)*>
             where N: Copy + AddAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn add_assign(&mut self, right: N) {
@@ -403,7 +403,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> SubAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> SubAssign<$vecn<N $(, $param)*>> for $vecn<N $(, $param)*>
             where N: Copy + SubAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn sub_assign(&mut self, right: $vecn<N $(, $param)*>) {
@@ -415,7 +415,7 @@ macro_rules! vecn_dvec_common_impl(
             }
         }
 
-        impl<N> SubAssign<N> for $vecn<N $(, $param)*>
+        impl<N $(, $param: ArrayLength<N>)*> SubAssign<N> for $vecn<N $(, $param)*>
             where N: Copy + SubAssign<N> + Zero $(, $param : ArrayLength<N>)* {
             #[inline]
             fn sub_assign(&mut self, right: N) {