diff --git a/src/lib.rs b/src/lib.rs
index aa54d2e..ef2f92c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -131,7 +131,10 @@ unsafe fn avx2_support_no_cache_x86() -> bool {
 mod tests {
     use crate::decode::{hex_decode, hex_decode_with_case, CheckCase};
     use crate::encode::{hex_encode, hex_string};
-    use crate::{hex_encode_upper, hex_string_upper, vectorization_support, Vectorization};
+    use crate::{hex_encode_upper, vectorization_support, Vectorization};
+    #[cfg(feature = "alloc")]
+    use crate::hex_string_upper;
+
     use proptest::proptest;
 
     #[cfg(not(feature = "alloc"))]
@@ -169,6 +172,7 @@ mod tests {
             assert_eq!(hex_string.as_str(), hex::encode(s));
         }
 
+	#[cfg(feature = "alloc")]
         {
             let encode_upper = &*hex_encode_upper(s.as_bytes(), &mut buffer).unwrap();
 
@@ -214,6 +218,7 @@ mod tests {
 
             assert_eq!(&dst[..], s.as_bytes());
         }
+	#[cfg(feature = "alloc")]
         {
             let mut dst = Vec::with_capacity(len);
             dst.resize(len, 0);