diff --git a/pkcs1/src/params.rs b/pkcs1/src/params.rs
index c0bab6b40..3381c2b48 100644
--- a/pkcs1/src/params.rs
+++ b/pkcs1/src/params.rs
@@ -152,8 +152,6 @@ impl<'a> RsaPssParamsRef<'a> {
 impl<Params> RsaPssParams<Params>
 where
     AlgorithmIdentifier<Params>: AsAlgorithmIdentifierRef,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifier<AnyRef<'static>>>,
-    Params: PartialEq,
 {
     fn context_specific_hash(&self) -> Option<ContextSpecificRef<'_, AlgorithmIdentifier<Params>>> {
         if self.hash.as_algo_ref() == SHA_1_AI {
@@ -170,7 +168,7 @@ where
     fn context_specific_mask_gen(
         &self,
     ) -> Option<ContextSpecificRef<'_, AlgorithmIdentifier<AlgorithmIdentifier<Params>>>> {
-        if self.mask_gen == default_mgf1_sha1::<Params>() {
+        if is_default_mgf1_sha1(&self.mask_gen) {
             None
         } else {
             Some(ContextSpecificRef {
@@ -201,7 +199,7 @@ where
     AlgorithmIdentifier<Params>: DecodeValue<'a, Error = der::Error> + FixedTag,
     AlgorithmIdentifier<AlgorithmIdentifier<Params>>:
         DecodeValue<'a, Error = der::Error> + FixedTag,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
+    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'a>>,
     Params: 'a,
 {
     type Error = der::Error;
@@ -230,8 +228,6 @@ where
     for<'b> Option<ContextSpecificRef<'b, AlgorithmIdentifier<Params>>>: Encode,
     for<'b> Option<ContextSpecificRef<'b, AlgorithmIdentifier<AlgorithmIdentifier<Params>>>>:
         Encode,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
-    Params: PartialEq,
 {
     fn value_len(&self) -> der::Result<Length> {
         self.context_specific_hash().encoded_len()?
@@ -256,7 +252,7 @@ where
     AlgorithmIdentifier<Params>: DecodeValue<'a, Error = der::Error> + FixedTag,
     AlgorithmIdentifier<AlgorithmIdentifier<Params>>:
         DecodeValue<'a, Error = der::Error> + FixedTag,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
+    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'a>>,
     Params: 'a,
 {
     type Error = Error;
@@ -267,9 +263,9 @@ where
 }
 
 /// Default Mask Generation Function (MGF): SHA-1.
-fn default_mgf1_sha1<Params>() -> AlgorithmIdentifier<AlgorithmIdentifier<Params>>
+fn default_mgf1_sha1<'a, Params>() -> AlgorithmIdentifier<AlgorithmIdentifier<Params>>
 where
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
+    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'a>>,
 {
     AlgorithmIdentifier::<AlgorithmIdentifier<Params>> {
         oid: OID_MGF_1,
@@ -277,6 +273,19 @@ where
     }
 }
 
+/// Is `mask_gen` the default MGF (MGF1 with SHA-1)?
+fn is_default_mgf1_sha1<Params>(mask_gen: &AlgorithmIdentifier<AlgorithmIdentifier<Params>>) -> bool
+where
+    AlgorithmIdentifier<Params>: AsAlgorithmIdentifierRef,
+{
+    mask_gen.oid == OID_MGF_1
+        && mask_gen
+            .parameters
+            .as_ref()
+            .map(AsAlgorithmIdentifierRef::as_algo_ref)
+            == Some(SHA_1_AI)
+}
+
 /// [`RsaOaepParams`] with [`AlgorithmIdentifier<AnyRef>`]
 pub type RsaOaepParamsRef<'a> = RsaOaepParams<AnyRef<'a>>;
 
@@ -345,13 +354,11 @@ where
 impl<Params> RsaOaepParams<Params>
 where
     AlgorithmIdentifier<Params>: AsAlgorithmIdentifierRef,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
-    Params: PartialEq,
 {
     fn context_specific_mask_gen(
         &self,
     ) -> Option<ContextSpecificRef<'_, AlgorithmIdentifier<AlgorithmIdentifier<Params>>>> {
-        if self.mask_gen == default_mgf1_sha1::<Params>() {
+        if is_default_mgf1_sha1(&self.mask_gen) {
             None
         } else {
             Some(ContextSpecificRef {
@@ -412,7 +419,7 @@ where
     AlgorithmIdentifier<Params>: DecodeValue<'a, Error = der::Error> + FixedTag,
     AlgorithmIdentifier<AlgorithmIdentifier<Params>>:
         DecodeValue<'a, Error = der::Error> + FixedTag,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
+    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'a>>,
     Params: 'a,
 {
     type Error = der::Error;
@@ -438,8 +445,6 @@ where
     for<'b> Option<ContextSpecificRef<'b, AlgorithmIdentifier<Params>>>: Encode,
     for<'b> Option<ContextSpecificRef<'b, AlgorithmIdentifier<AlgorithmIdentifier<Params>>>>:
         Encode,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
-    Params: PartialEq,
 {
     fn value_len(&self) -> der::Result<Length> {
         self.context_specific_hash().encoded_len()?
@@ -462,7 +467,7 @@ where
     AlgorithmIdentifier<Params>: DecodeValue<'a, Error = der::Error> + FixedTag,
     AlgorithmIdentifier<AlgorithmIdentifier<Params>>:
         DecodeValue<'a, Error = der::Error> + FixedTag,
-    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'static>>,
+    AlgorithmIdentifier<Params>: From<AlgorithmIdentifierRef<'a>>,
     Params: 'a,
 {
     type Error = Error;
diff --git a/pkcs1/tests/params.rs b/pkcs1/tests/params.rs
index 32694f9ae..9025c500d 100644
--- a/pkcs1/tests/params.rs
+++ b/pkcs1/tests/params.rs
@@ -262,6 +262,32 @@ fn new_oaep_param() {
     );
 }
 
+/// The `*Ref` types borrow from their input, which need not be `'static`.
+#[test]
+fn ref_params_non_static_input() {
+    fn pss(der: &[u8], buf: &mut [u8]) -> usize {
+        let param = RsaPssParamsRef::try_from(der).unwrap();
+        param.encode_to_slice(buf).unwrap().len()
+    }
+    fn oaep(der: &[u8], buf: &mut [u8]) -> usize {
+        let param = RsaOaepParamsRef::try_from(der).unwrap();
+        param.encode_to_slice(buf).unwrap().len()
+    }
+
+    let mut buf = [0_u8; 256];
+    let mut der = [0_u8; 64];
+
+    let n = RSA_PSS_PARAMETERS_SHA2_256.len();
+    der[..n].copy_from_slice(RSA_PSS_PARAMETERS_SHA2_256);
+    assert_eq!(pss(&der[..n], &mut buf), n);
+    assert_eq!(&buf[..n], RSA_PSS_PARAMETERS_SHA2_256);
+
+    let n = RSA_OAEP_PARAMETERS_SHA2_256.len();
+    der[..n].copy_from_slice(RSA_OAEP_PARAMETERS_SHA2_256);
+    assert_eq!(oaep(&der[..n], &mut buf), n);
+    assert_eq!(&buf[..n], RSA_OAEP_PARAMETERS_SHA2_256);
+}
+
 #[cfg(feature = "alloc")]
 mod test_alloc_trait_bounds {
     use der::{Decode, Encode};