diff --git a/Cargo.toml b/Cargo.toml
index 2aefba8..59f6b40 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,8 +5,8 @@ name = "compiler_builtins"
 version = "0.1.0"
 
 [build-dependencies]
-cast = "0.2.0"
-rand = "0.3.15"
+cast = { version = "0.2.0", optional = true }
+rand = { version = "0.3.15", optional = true }
 
 [build-dependencies.gcc]
 optional = true
@@ -18,21 +18,14 @@ compiler-builtins = []
 default = ["compiler-builtins"]
 mem = []
 rustbuild = ["compiler-builtins"]
+# generate tests
+gen-tests = ["cast", "rand"]
 
-[target]
+[target.'cfg(all(target_arch = "arm", not(any(target_env = "gnu", target_env = "musl")), target_os = "linux"))'.dev-dependencies]
+test = { git = "https://github.com/japaric/utest" }
+utest-cortex-m-qemu = { default-features = false, git = "https://github.com/japaric/utest" }
+utest-macros = { git = "https://github.com/japaric/utest" }
 
-[target."cfg(all(target_arch = \"arm\", not(any(target_env = \"gnu\", target_env = \"musl\")), target_os = \"linux\"))"]
 
-[target."cfg(all(target_arch = \"arm\", not(any(target_env = \"gnu\", target_env = \"musl\")), target_os = \"linux\"))".dev-dependencies]
-
-[target."cfg(all(target_arch = \"arm\", not(any(target_env = \"gnu\", target_env = \"musl\")), target_os = \"linux\"))".dev-dependencies.test]
-git = "https://github.com/japaric/utest"
-
-[target."cfg(all(target_arch = \"arm\", not(any(target_env = \"gnu\", target_env = \"musl\")), target_os = \"linux\"))".dev-dependencies.utest-cortex-m-qemu]
-default-features = false
-git = "https://github.com/japaric/utest"
-
-[target."cfg(all(target_arch = \"arm\", not(any(target_env = \"gnu\", target_env = \"musl\")), target_os = \"linux\"))".dev-dependencies.utest-macros]
-git = "https://github.com/japaric/utest"
 
 [workspace]
diff --git a/build.rs b/build.rs
index 2c8cff7..ac75e6e 100644
--- a/build.rs
+++ b/build.rs
@@ -18,6 +18,7 @@ fn main() {
     let llvm_target = target.split('-').collect::<Vec<_>>();
 
     // Build test files
+    #[cfg(feature = "gen-tests")]
     tests::generate();
 
     // Build missing intrinsics from compiler-rt C source code
@@ -36,6 +37,7 @@ fn main() {
     }
 }
 
+#[cfg(feature = "gen-tests")]
 mod tests {
     extern crate cast;
     extern crate rand;
diff --git a/ci/run.sh b/ci/run.sh
index 17c54ef..771f881 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -25,16 +25,16 @@ case $1 in
                 ;;
             esac
 
-            xargo test --test $t --target $1 --features mem --no-run
+            xargo test --test $t --target $1 --features 'mem gen-tests' --no-run
             qemu-arm-static target/${1}/debug/$t-*
 
-            xargo test --test $t --target $1 --features mem --no-run --release
+            xargo test --test $t --target $1 --features 'mem gen-tests' --no-run --release
             qemu-arm-static target/${1}/release/$t-*
         done
         ;;
     *)
-        cargo test --no-default-features --target $1
-        cargo test --no-default-features --target $1 --release
+        cargo test --no-default-features --features gen-tests --target $1
+        cargo test --no-default-features --features gen-tests --target $1 --release
         ;;
 esac