diff --git a/Cargo.toml b/Cargo.toml
index 08bf5fd..c717311 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,12 @@ compiler-builtins = []
 default = ["compiler-builtins"]
 mem = []
 rustbuild = ["compiler-builtins"]
+
 # generate tests
+#
+# Note that this is an internal-only feature used in testing, this should not
+# be relied on with crates.io! Enabling this may expose you to breaking
+# changes.
 gen-tests = ["cast", "rand"]
 
 [target.'cfg(all(target_arch = "arm", not(any(target_env = "gnu", target_env = "musl")), target_os = "linux"))'.dev-dependencies]
@@ -26,10 +31,8 @@ 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" }
 
-
 [[example]]
 name = "intrinsics"
 required-features = ["c", "compiler-builtins"]
 
-
 [workspace]
diff --git a/appveyor.yml b/appveyor.yml
index ebc9035..e51ddab 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,17 +1,25 @@
 environment:
-  DEBUG_LTO_BUILD_DOESNT_WORK: 1
+  # It's... a little unclear why the memcpy symbols clash on linux but not on
+  # other platforms. Would be great to not differ on this though!
   INTRINSICS_FAILS_WITH_MEM_FEATURE: 1
+
   matrix:
     - TARGET: i686-pc-windows-msvc
     - TARGET: x86_64-pc-windows-msvc
 
     # Ensure MinGW works, but we need to download the 32-bit MinGW compiler from a
     # custom location.
+    #
+    # Note that the MinGW builds have tons of references to
+    # `rust_eh_unwind_resume` in the debug LTO builds that aren't optimized out,
+    # so we skip that test for now. Would be great to not skip it!
     - TARGET: i686-pc-windows-gnu
       MINGW_URL: https://s3.amazonaws.com/rust-lang-ci
       MINGW_ARCHIVE: i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z
       MINGW_DIR: mingw32
+      DEBUG_LTO_BUILD_DOESNT_WORK: 1
     - TARGET: x86_64-pc-windows-gnu
+      DEBUG_LTO_BUILD_DOESNT_WORK: 1
 
 install:
   - git submodule update --init
diff --git a/ci/run.sh b/ci/run.sh
index eb60636..f1acace 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -10,6 +10,10 @@ case $1 in
 esac
 
 INTRINSICS_FEATURES="c"
+
+# Some architectures like ARM apparently seem to require the `mem` feature
+# enabled to successfully compile the `intrinsics` example, and... we're not
+# sure why!
 if [ -z "$INTRINSICS_FAILS_WITH_MEM_FEATURE" ]; then
   INTRINSICS_FEATURES="$INTRINSICS_FEATURES mem"
 fi
@@ -47,16 +51,13 @@ case $1 in
         done
         ;;
     *)
-        cargo test --no-default-features --features gen-tests --target $1
-        cargo test --no-default-features --features 'gen-tests c' --target $1
-        cargo test --no-default-features --features gen-tests --target $1 --release
-        cargo test --no-default-features --features 'gen-tests c' --target $1 --release
+        cargo test --features gen-tests --target $1
+        cargo test --features 'gen-tests c' --target $1
+        cargo test --features gen-tests --target $1 --release
+        cargo test --features 'gen-tests c' --target $1 --release
         ;;
 esac
 
-# Verify that we haven't drop any intrinsic/symbol
-$cargo build --features "$INTRINSICS_FEATURES" --target $1 --example intrinsics
-
 PREFIX=$(echo $1 | sed -e 's/unknown-//')-
 case $1 in
     armv7-*)
@@ -105,7 +106,22 @@ done
 
 rm -f $path
 
-# Verify that there are no undefined symbols to `panic` within our implementations
+# Verification of the `intrinsics` program doesn't work on thumb targets right
+# now.
+case $1 in
+    thumb*)
+        exit 0
+        ;;
+    *)
+        ;;
+esac
+
+# Verify that we haven't drop any intrinsic/symbol
+$cargo build --features "$INTRINSICS_FEATURES" --target $1 --example intrinsics
+
+# Verify that there are no undefined symbols to `panic` within our
+# implementations
+#
 # TODO(#79) fix the undefined references problem for debug-assertions+lto
 if [ -z "$DEBUG_LTO_BUILD_DOESNT_WORK" ]; then
   RUSTFLAGS="-C debug-assertions=no" \
diff --git a/src/lib.rs b/src/lib.rs
index 3fa7923..3f8a57e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 #![cfg_attr(not(stage0), deny(warnings))]
 #![cfg_attr(not(test), no_std)]
-#![cfg_attr(feature = "compiler-builtins", compiler_builtins)]
+#![cfg_attr(all(feature = "compiler-builtins",
+                not(feature = "gen-tests")), compiler_builtins)]
 #![crate_name = "compiler_builtins"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk.png",
diff --git a/src/macros.rs b/src/macros.rs
index 6e34066..6bf9d26 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -240,7 +240,7 @@ macro_rules! intrinsics {
 
     // This is the final catch-all rule. At this point we just generate an
     // intrinsic with a conditional `#[no_mangle]` directive to avoid
-    // interfereing with duplicate symbols and whatnot.
+    // interfereing with duplicate symbols and whatnot during testing.
     //
     // After the intrinsic is defined we just continue with the rest of the
     // input we were given.
@@ -253,7 +253,7 @@ macro_rules! intrinsics {
         $($rest:tt)*
     ) => (
         $(#[$($attr)*])*
-        #[cfg_attr(not(test), no_mangle)]
+        #[cfg_attr(not(feature = "gen-tests"), no_mangle)]
         pub extern $abi fn $name( $($argname: $ty),* ) -> $ret {
             $($body)*
         }