diff --git a/Cargo.lock b/Cargo.lock
index cc4f5af1dfb..2c7c5379385 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -295,6 +295,7 @@ dependencies = [
  "reqwest",
  "scheduled-thread-pool",
  "semver 0.10.0",
+ "semver 0.11.0",
  "sentry",
  "serde",
  "serde_json",
diff --git a/Cargo.toml b/Cargo.toml
index 03b1550eb9c..f58110dd8a9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -72,7 +72,8 @@ parking_lot = "0.11"
 rand = "0.7"
 reqwest = { version = "0.11", features = ["blocking", "gzip", "json"] }
 scheduled-thread-pool = "0.2.0"
-semver = { version = "0.10", features = ["diesel", "serde"] }
+semver = { version = "0.10", features = ["diesel", "serde"] } # TODO: Bump to 0.11 after steveklabnik/semver#217 is resolved
+semver_next = { version = "0.11", package = "semver" }
 sentry = "0.22"
 serde = { version = "1.0.0", features = ["derive"] }
 serde_json = "1.0.0"
diff --git a/src/admin/mod.rs b/src/admin/mod.rs
index fd08ad49d73..99ce3efbea4 100644
--- a/src/admin/mod.rs
+++ b/src/admin/mod.rs
@@ -4,6 +4,7 @@ pub mod dialoguer;
 pub mod on_call;
 pub mod populate;
 pub mod render_readmes;
+pub mod test_new_semver_release;
 pub mod test_pagerduty;
 pub mod transfer_crates;
 pub mod verify_token;
diff --git a/src/admin/test_new_semver_release.rs b/src/admin/test_new_semver_release.rs
new file mode 100644
index 00000000000..b7923a19f8f
--- /dev/null
+++ b/src/admin/test_new_semver_release.rs
@@ -0,0 +1,71 @@
+use crate::{
+    db,
+    schema::{dependencies, versions},
+};
+
+use clap::Clap;
+use diesel::prelude::*;
+
+#[derive(Clap, Copy, Clone, Debug)]
+#[clap(
+    name = "test-new-semver-release",
+    about = "Scan the database for all versions and version requirements to \
+        ensure they can be parsed by the latest `semver` crate."
+)]
+pub struct Opts {}
+
+pub fn run(_opts: Opts) {
+    use self::dependencies::dsl::*;
+    use self::versions::dsl::*;
+
+    let url = db::connection_url(&dotenv::var("READ_ONLY_REPLICA_URL").unwrap());
+    let conn = PgConnection::establish(&url).unwrap();
+    conn.transaction::<_, diesel::result::Error, _>(|| {
+        let vers = versions.select(num).load(&conn)?;
+        test_versions(&vers);
+
+        let deps = dependencies.select(req).load(&conn)?;
+        test_dependency_predicates(&deps);
+
+        Ok(())
+    })
+    .unwrap();
+
+    println!("Test finished.");
+}
+
+fn test_versions(versions: &[String]) {
+    for version in versions {
+        if let Err(e) = semver::Version::parse(version) {
+            println!("Could not parse `{}` as a semver::Version: {}", version, e);
+        }
+    }
+
+    for version in versions {
+        if let Err(e) = semver::Version::parse(version) {
+            println!("Could not parse `{}` as a semver::Version: {}", version, e);
+        }
+
+        if let Err(e) = semver_next::Version::parse(version) {
+            println!(
+                "Could not parse `{}` as a semver_next::Version: {}",
+                version, e
+            );
+        }
+    }
+}
+
+fn test_dependency_predicates(versions: &[String]) {
+    for version in versions {
+        if let Err(e) = semver::VersionReq::parse(version) {
+            println!("Could not parse `{}` as a semver::Version: {}", version, e);
+        }
+
+        if let Err(e) = semver_next::VersionReq::parse(version) {
+            println!(
+                "Could not parse `{}` as a semver_next::Version: {}",
+                version, e
+            );
+        }
+    }
+}
diff --git a/src/bin/crates-admin.rs b/src/bin/crates-admin.rs
index f8b70179f00..ea54b2d6ff2 100644
--- a/src/bin/crates-admin.rs
+++ b/src/bin/crates-admin.rs
@@ -1,8 +1,8 @@
 #![warn(clippy::all, rust_2018_idioms)]
 
 use cargo_registry::admin::{
-    delete_crate, delete_version, populate, render_readmes, test_pagerduty, transfer_crates,
-    verify_token,
+    delete_crate, delete_version, populate, render_readmes, test_new_semver_release,
+    test_pagerduty, transfer_crates, verify_token,
 };
 
 use clap::Clap;
@@ -20,6 +20,7 @@ enum SubCommand {
     DeleteVersion(delete_version::Opts),
     Populate(populate::Opts),
     RenderReadmes(render_readmes::Opts),
+    TestNewSemverRelease(test_new_semver_release::Opts),
     TestPagerduty(test_pagerduty::Opts),
     TransferCrates(transfer_crates::Opts),
     VerifyToken(verify_token::Opts),
@@ -33,6 +34,7 @@ fn main() {
         SubCommand::DeleteVersion(opts) => delete_version::run(opts),
         SubCommand::Populate(opts) => populate::run(opts),
         SubCommand::RenderReadmes(opts) => render_readmes::run(opts),
+        SubCommand::TestNewSemverRelease(opts) => test_new_semver_release::run(opts),
         SubCommand::TestPagerduty(opts) => test_pagerduty::run(opts).unwrap(),
         SubCommand::TransferCrates(opts) => transfer_crates::run(opts),
         SubCommand::VerifyToken(opts) => verify_token::run(opts).unwrap(),
diff --git a/src/controllers/krate/publish.rs b/src/controllers/krate/publish.rs
index 1257faa2728..e07f77f863e 100644
--- a/src/controllers/krate/publish.rs
+++ b/src/controllers/krate/publish.rs
@@ -25,7 +25,8 @@ pub const MISSING_RIGHTS_ERROR_MESSAGE: &str =
      to accept an invitation to be an owner before \
      publishing.";
 
-pub const WILDCARD_ERROR_MESSAGE: &str = "wildcard (`*`) dependency constraints are not allowed \
+pub const WILDCARD_ERROR_MESSAGE: &str =
+    "wildcard (`*` or `>= 0`) dependency constraints are not allowed \
      on crates.io. See https://doc.rust-lang.org/cargo/faq.html#can-\
      libraries-use--as-a-version-for-their-dependencies for more \
      information";
diff --git a/src/tests/all.rs b/src/tests/all.rs
index ac54f3ea53e..1222f2fafc4 100644
--- a/src/tests/all.rs
+++ b/src/tests/all.rs
@@ -178,6 +178,7 @@ fn env(var: &str) -> String {
     }
 }
 
+#[track_caller]
 fn json<T>(r: &mut AppResponse) -> T
 where
     for<'de> T: serde::Deserialize<'de>,
diff --git a/src/tests/version.rs b/src/tests/version.rs
index 6f059f2e5e4..93c9e4ae099 100644
--- a/src/tests/version.rs
+++ b/src/tests/version.rs
@@ -162,3 +162,28 @@ fn version_size() {
         .expect("Could not find v2.0.0");
     assert_eq!(version2.crate_size, Some(91));
 }
+
+#[test]
+fn accepts_complicated_semver_prerelease_and_build_identifiers() {
+    #[track_caller]
+    fn parse(s: &str) {
+        semver::Version::parse(s).expect("couldn't parse as Version");
+        semver::VersionReq::parse(s).expect("couldn't parse as VersionReq");
+    }
+
+    // Must provide at least major, minor, and patch so that it can parse as a Version
+    parse("1.0.0");
+
+    parse("1.0.0-1a");
+    parse("1.0.0-1.a");
+    parse("1.0.0-a1");
+    parse("1.0.0-a.1");
+
+    parse("1.0.0+01a");
+    parse("1.0.0+1.a");
+    parse("1.0.0+a01");
+    parse("1.0.0+a.01");
+
+    parse("1.0.0-01+01");
+    parse("1.0.0-01.-.a+01.a-01a-01a");
+}