diff --git a/Cargo.toml b/Cargo.toml
index e6724af..ac626eb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,12 +13,14 @@ include = ["src/**/*", "benches/**/*", "tests/**/*", "LICENSE", "README.md", "CH
 
 [dependencies]
 serde_json = "1.0"
-serde = {version = "1.0", features = ["derive"] }
+serde = { version = "1.0", features = ["derive"] }
 ring = { version = "0.16.5", features = ["std"] }
 base64 = "0.13"
 # For PEM decoding
-pem = {version = "1", optional = true}
-simple_asn1 = {version = "0.6", optional = true}
+pem = { version = "1", optional = true }
+simple_asn1 = { version = "0.6", optional = true }
+time = "0.3"
+wasm-time = { path = "../wasm-time" }
 
 [dev-dependencies]
 # For the custom time example
@@ -28,6 +30,8 @@ criterion = "0.3"
 [features]
 default = ["use_pem"]
 use_pem = ["pem", "simple_asn1"]
+no_verify = []
+wasm = ["no_verify"]
 
 [[bench]]
 name = "jwt"
diff --git a/src/decoding.rs b/src/decoding.rs
index 145a24d..aad2975 100644
--- a/src/decoding.rs
+++ b/src/decoding.rs
@@ -1,6 +1,7 @@
 use serde::de::DeserializeOwned;
 
 use crate::algorithms::AlgorithmFamily;
+#[cfg(not(feature = "no_verify"))]
 use crate::crypto::verify;
 use crate::errors::{new_error, ErrorKind, Result};
 use crate::header::Header;
@@ -172,8 +173,13 @@ fn verify_signature<'a>(
         return Err(new_error(ErrorKind::InvalidAlgorithm));
     }
 
-    if validation.validate_signature && !verify(signature, message.as_bytes(), key, header.alg)? {
-        return Err(new_error(ErrorKind::InvalidSignature));
+    if validation.validate_signature {
+        #[cfg(not(feature = "no_verify"))]
+        if !verify(signature, message.as_bytes(), key, header.alg)? {
+            return Err(new_error(ErrorKind::InvalidSignature));
+        }
+        #[cfg(feature = "no_verify")]
+        return Err(new_error(ErrorKind::VerificationNotSupported));
     }
 
     Ok((header, payload))
@@ -207,7 +213,7 @@ pub fn decode<T: DeserializeOwned>(
         Ok((header, claims)) => {
             let decoded_claims = DecodedJwtPartClaims::from_jwt_part_claims(claims)?;
             let claims = decoded_claims.deserialize()?;
-            validate(decoded_claims.deserialize()?, validation)?;
+            validate(&decoded_claims.deserialize()?, validation)?;
 
             Ok(TokenData { header, claims })
         }
diff --git a/src/errors.rs b/src/errors.rs
index e0553e3..48e3b50 100644
--- a/src/errors.rs
+++ b/src/errors.rs
@@ -78,6 +78,10 @@ pub enum ErrorKind {
     Utf8(::std::string::FromUtf8Error),
     /// Something unspecified went wrong with crypto
     Crypto(::ring::error::Unspecified),
+
+    /// Verification is disabled by the feature flag `no_verify`.
+    #[cfg(feature = "no_verify")]
+    VerificationNotSupported,
 }
 
 impl StdError for Error {
@@ -102,6 +106,8 @@ impl StdError for Error {
             ErrorKind::Json(ref err) => Some(err.as_ref()),
             ErrorKind::Utf8(ref err) => Some(err),
             ErrorKind::Crypto(ref err) => Some(err),
+            #[cfg(feature = "no_verify")]
+            ErrorKind::VerificationNotSupported => None,
         }
     }
 }
@@ -128,6 +134,8 @@ impl fmt::Display for Error {
             ErrorKind::Utf8(ref err) => write!(f, "UTF-8 error: {}", err),
             ErrorKind::Crypto(ref err) => write!(f, "Crypto error: {}", err),
             ErrorKind::Base64(ref err) => write!(f, "Base64 error: {}", err),
+            #[cfg(feature = "no_verify")]
+            ErrorKind::VerificationNotSupported => write!(f, "{:?}", self.0),
         }
     }
 }
diff --git a/src/validation.rs b/src/validation.rs
index 1a13eea..dc32189 100644
--- a/src/validation.rs
+++ b/src/validation.rs
@@ -2,7 +2,6 @@ use std::borrow::Cow;
 use std::collections::HashSet;
 use std::fmt;
 use std::marker::PhantomData;
-use std::time::{SystemTime, UNIX_EPOCH};
 
 use serde::de::{self, Visitor};
 use serde::{Deserialize, Deserializer};
@@ -136,10 +135,13 @@ impl Default for Validation {
     }
 }
 
+
 /// Gets the current timestamp in the format JWT expect
 pub fn get_current_timestamp() -> u64 {
-    let start = SystemTime::now();
-    start.duration_since(UNIX_EPOCH).expect("Time went backwards").as_secs()
+    let start = wasm_time::now_utc();
+    let secs = (start - time::OffsetDateTime::UNIX_EPOCH).whole_seconds();
+    assert!(secs >= 0, "Time went backwards.");
+    secs as u64
 }
 
 #[derive(Deserialize)]
@@ -212,7 +214,7 @@ fn is_subset(reference: &HashSet<String>, given: &HashSet<BorrowedCowIfPossible<
     }
 }
 
-pub(crate) fn validate(claims: ClaimsForValidation, options: &Validation) -> Result<()> {
+pub(crate) fn validate(claims: &ClaimsForValidation, options: &Validation) -> Result<()> {
     let now = get_current_timestamp();
 
     for required_claim in &options.required_spec_claims {
@@ -231,27 +233,27 @@ pub(crate) fn validate(claims: ClaimsForValidation, options: &Validation) -> Res
     }
 
     if options.validate_exp
-        && !matches!(claims.exp, TryParse::Parsed(exp) if exp >= now-options.leeway)
+        && !matches!(claims.exp, TryParse::Parsed(ref exp) if *exp >= now-options.leeway)
     {
         return Err(new_error(ErrorKind::ExpiredSignature));
     }
 
     if options.validate_nbf
-        && !matches!(claims.nbf, TryParse::Parsed(nbf) if nbf <= now + options.leeway)
+        && !matches!(claims.nbf, TryParse::Parsed(ref nbf) if *nbf <= now + options.leeway)
     {
         return Err(new_error(ErrorKind::ImmatureSignature));
     }
 
     if let Some(correct_sub) = options.sub.as_deref() {
-        if !matches!(claims.sub, TryParse::Parsed(sub) if sub == correct_sub) {
+        if !matches!(claims.sub, TryParse::Parsed(ref sub) if *sub == correct_sub) {
             return Err(new_error(ErrorKind::InvalidSubject));
         }
     }
 
     if let Some(ref correct_iss) = options.iss {
         let is_valid = match claims.iss {
-            TryParse::Parsed(Issuer::Single(iss)) if correct_iss.contains(&*iss) => true,
-            TryParse::Parsed(Issuer::Multiple(iss)) => is_subset(correct_iss, &iss),
+            TryParse::Parsed(Issuer::Single(ref iss)) if correct_iss.contains(&**iss) => true,
+            TryParse::Parsed(Issuer::Multiple(ref iss)) => is_subset(correct_iss, &iss),
             _ => false,
         };
 
@@ -262,8 +264,8 @@ pub(crate) fn validate(claims: ClaimsForValidation, options: &Validation) -> Res
 
     if let Some(ref correct_aud) = options.aud {
         let is_valid = match claims.aud {
-            TryParse::Parsed(Audience::Single(aud)) if correct_aud.contains(&*aud) => true,
-            TryParse::Parsed(Audience::Multiple(aud)) => is_subset(correct_aud, &aud),
+            TryParse::Parsed(Audience::Single(ref aud)) if correct_aud.contains(&**aud) => true,
+            TryParse::Parsed(Audience::Multiple(ref aud)) => is_subset(correct_aud, &aud),
             _ => false,
         };
 
@@ -330,21 +332,21 @@ mod tests {
     #[test]
     fn exp_in_future_ok() {
         let claims = json!({ "exp": get_current_timestamp() + 10000 });
-        let res = validate(deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
+        let res = validate(&deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
         assert!(res.is_ok());
     }
 
     #[test]
     fn exp_float_in_future_ok() {
         let claims = json!({ "exp": (get_current_timestamp() as f64) + 10000.123 });
-        let res = validate(deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
+        let res = validate(&deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
         assert!(res.is_ok());
     }
 
     #[test]
     fn exp_in_past_fails() {
         let claims = json!({ "exp": get_current_timestamp() - 100000 });
-        let res = validate(deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
+        let res = validate(&deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -356,7 +358,7 @@ mod tests {
     #[test]
     fn exp_float_in_past_fails() {
         let claims = json!({ "exp": (get_current_timestamp() as f64) - 100000.1234 });
-        let res = validate(deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
+        let res = validate(&deserialize_claims(&claims), &Validation::new(Algorithm::HS256));
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -370,7 +372,7 @@ mod tests {
         let claims = json!({ "exp": get_current_timestamp() - 500 });
         let mut validation = Validation::new(Algorithm::HS256);
         validation.leeway = 1000 * 60;
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -380,7 +382,7 @@ mod tests {
         let claims = json!({});
         let mut validation = Validation::new(Algorithm::HS256);
         validation.required_spec_claims = HashSet::new();
-        let res = validate(deserialize_claims(&claims), &validation).unwrap_err();
+        let res = validate(&deserialize_claims(&claims), &validation).unwrap_err();
         assert_eq!(res.kind(), &ErrorKind::ExpiredSignature);
     }
 
@@ -391,7 +393,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.validate_nbf = true;
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -402,7 +404,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.validate_nbf = true;
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -413,7 +415,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.validate_nbf = true;
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -430,7 +432,7 @@ mod tests {
         validation.validate_exp = false;
         validation.validate_nbf = true;
         validation.leeway = 1000 * 60;
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -441,7 +443,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.set_issuer(&["Keats"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -452,7 +454,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.set_issuer(&["UserA", "UserB"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -464,7 +466,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.set_issuer(&["Keats"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -481,7 +483,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.set_issuer(&["Keats"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
 
         match res.unwrap_err().kind() {
             ErrorKind::InvalidIssuer => (),
@@ -496,7 +498,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.sub = Some("Keats".to_owned());
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -507,7 +509,7 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.validate_exp = false;
         validation.sub = Some("Keats".to_owned());
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -523,7 +525,7 @@ mod tests {
         validation.validate_exp = false;
         validation.required_spec_claims = HashSet::new();
         validation.sub = Some("Keats".to_owned());
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -539,7 +541,7 @@ mod tests {
         validation.validate_exp = false;
         validation.required_spec_claims = HashSet::new();
         validation.set_audience(&["Everyone"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -550,7 +552,7 @@ mod tests {
         validation.validate_exp = false;
         validation.required_spec_claims = HashSet::new();
         validation.set_audience(&["UserA", "UserB"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
@@ -561,7 +563,7 @@ mod tests {
         validation.validate_exp = false;
         validation.required_spec_claims = HashSet::new();
         validation.set_audience(&["UserA", "UserB"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -577,7 +579,7 @@ mod tests {
         validation.validate_exp = false;
         validation.required_spec_claims = HashSet::new();
         validation.set_audience(&["None"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -593,7 +595,7 @@ mod tests {
         validation.validate_exp = false;
         validation.required_spec_claims = HashSet::new();
         validation.set_audience(&["None"]);
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_err());
 
         match res.unwrap_err().kind() {
@@ -612,7 +614,7 @@ mod tests {
         validation.set_issuer(&["iss no check"]);
         validation.set_audience(&["iss no check"]);
 
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         // It errors because it needs to validate iss/sub which are missing
         assert!(res.is_err());
         match res.unwrap_err().kind() {
@@ -634,14 +636,14 @@ mod tests {
         validation.required_spec_claims = HashSet::new();
         validation.set_audience(&["my-googleclientid1234.apps.googleusercontent.com"]);
 
-        let res = validate(deserialize_claims(&claims), &validation);
+        let res = validate(&deserialize_claims(&claims), &validation);
         assert!(res.is_ok());
     }
 
     #[test]
     fn errors_when_required_claim_is_missing() {
         let claims = json!({});
-        let res = validate(deserialize_claims(&claims), &Validation::default()).unwrap_err();
+        let res = validate(&deserialize_claims(&claims), &Validation::default()).unwrap_err();
         assert_eq!(res.kind(), &ErrorKind::MissingRequiredClaim("exp".to_owned()));
     }
 }