diff --git a/crates/core_simd/src/lane_count.rs b/crates/core_simd/src/lane_count.rs
index 4a5dc80049a9e2cd73b9b78cbd2bab9e4fc14be3..3b316f12b3e56f50216975c555fac45cb2f6b8f8 100644
--- a/crates/core_simd/src/lane_count.rs
+++ b/crates/core_simd/src/lane_count.rs
@@ -37,3 +37,6 @@ impl SupportedLaneCount for LaneCount<16> {
 impl SupportedLaneCount for LaneCount<32> {
     type BitMask = [u8; 4];
 }
+impl SupportedLaneCount for LaneCount<64> {
+    type BitMask = [u8; 8];
+}
diff --git a/crates/test_helpers/src/lib.rs b/crates/test_helpers/src/lib.rs
index 5c6478876f30be88797794d6c571fceb62193a1a..7edd609638171da96b1d7b9c38d3740a6f3724e8 100644
--- a/crates/test_helpers/src/lib.rs
+++ b/crates/test_helpers/src/lib.rs
@@ -376,6 +376,12 @@ fn lanes_16() {
                 fn lanes_32() {
                     implementation::<32>();
                 }
+
+                #[test]
+                #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
+                fn lanes_64() {
+                    implementation::<64>();
+                }
             }
         )*
     }
@@ -431,6 +437,12 @@ fn lanes_16() {
                 fn lanes_32() {
                     implementation::<32>();
                 }
+
+                #[test]
+                #[should_panic]
+                fn lanes_64() {
+                    implementation::<64>();
+                }
             }
         )*
     }