diff --git a/lib/LibeventReactor.php b/lib/LibeventReactor.php
index 9956753..ffbb607 100644
--- a/lib/LibeventReactor.php
+++ b/lib/LibeventReactor.php
@@ -129,27 +129,6 @@ class LibeventReactor implements SignalReactor {
         $this->isRunning = false;
     }
 
-    /**
-     * {@inheritDoc}
-     * @throws \InvalidArgumentException On invalid future time
-     */
-    public function at(callable $callback, $unixTimeOrStr): string {
-        $now = time();
-        if (is_int($unixTimeOrStr) && $unixTimeOrStr > $now) {
-            $secondsUntil = ($unixTimeOrStr - $now);
-        } elseif (($executeAt = @strtotime($unixTimeOrStr)) && $executeAt > $now) {
-            $secondsUntil = ($executeAt - $now);
-        } else {
-            throw new \InvalidArgumentException(
-                "Unix timestamp or future time string (parsable by strtotime()) required"
-            );
-        }
-
-        $msDelay = $secondsUntil * $this->resolution;
-
-        return $this->once($callback, $msDelay);
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/lib/NativeReactor.php b/lib/NativeReactor.php
index 547e4d9..eea7a21 100644
--- a/lib/NativeReactor.php
+++ b/lib/NativeReactor.php
@@ -213,26 +213,6 @@ class NativeReactor implements Reactor {
         }
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    public function at(callable $callback, $unixTimeOrStr): string {
-        $now = time();
-        if (is_int($unixTimeOrStr) && $unixTimeOrStr > $now) {
-            $secondsUntil = ($unixTimeOrStr - $now);
-        } elseif (($executeAt = @strtotime($unixTimeOrStr)) && $executeAt > $now) {
-            $secondsUntil = ($executeAt - $now);
-        } else {
-            throw new \InvalidArgumentException(
-                'Unix timestamp or future time string (parsable by strtotime()) required'
-            );
-        }
-
-        $msDelay = $secondsUntil * $this->resolution;
-
-        return $this->once($callback, $msDelay);
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/lib/Reactor.php b/lib/Reactor.php
index 28b3f48..ff37af6 100644
--- a/lib/Reactor.php
+++ b/lib/Reactor.php
@@ -52,15 +52,6 @@ interface Reactor {
      */
     public function repeat(callable $func, int $millisecondDelay): string;
 
-    /**
-     * Schedule an event to trigger once at the specified time
-     *
-     * @param callable $func A callback to invoke at the specified future time
-     * @param int|string $unixTimeOrStr
-     * @return string Returns unique (to the process) string watcher ID
-     */
-    public function at(callable $func, $unixTimeOrStr): string;
-
     /**
      * Watch a stream resource for readable data and trigger the callback when actionable
      *
diff --git a/lib/UvReactor.php b/lib/UvReactor.php
index 5c5dfeb..2242b28 100644
--- a/lib/UvReactor.php
+++ b/lib/UvReactor.php
@@ -228,26 +228,6 @@ class UvReactor implements SignalReactor {
         }
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    public function at(callable $callback, $unixTimeOrStr): string {
-        $now = time();
-        if (is_int($unixTimeOrStr) && $unixTimeOrStr > $now) {
-            $secondsUntil = ($unixTimeOrStr - $now);
-        } elseif (($executeAt = @strtotime($unixTimeOrStr)) && $executeAt > $now) {
-            $secondsUntil = ($executeAt - $now);
-        } else {
-            throw new \InvalidArgumentException(
-                'Unix timestamp or future time string (parsable by strtotime()) required'
-            );
-        }
-
-        $msDelay = $secondsUntil * $this->resolution;
-
-        return $this->once($callback, $msDelay);
-    }
-
     /**
      * {@inheritDoc}
      */