diff --git a/src/unit/ArcanistUnitTestResult.php b/src/unit/ArcanistUnitTestResult.php
index 74805581..f570c072 100644
--- a/src/unit/ArcanistUnitTestResult.php
+++ b/src/unit/ArcanistUnitTestResult.php
@@ -57,11 +57,30 @@ final class ArcanistUnitTestResult extends Phobject {
     return $this->result;
   }
 
+
+  /**
+   * Set the number of seconds spent executing this test.
+   *
+   * Reporting this information can help users identify slow tests and reduce
+   * the total cost of running a test suite.
+   *
+   * Callers should pass an integer or a float. For example, pass `3` for
+   * 3 seconds, or `0.125` for 125 milliseconds.
+   *
+   * @param int|float Duration, in seconds.
+   * @return this
+   */
   public function setDuration($duration) {
+    if (!is_int($duration) && !is_float($duration)) {
+      throw new Exception(
+        pht(
+          'Parameter passed to setDuration() must be an integer or a float.'));
+    }
     $this->duration = $duration;
     return $this;
   }
 
+
   public function getDuration() {
     return $this->duration;
   }
diff --git a/src/unit/parser/ArcanistGoTestResultParser.php b/src/unit/parser/ArcanistGoTestResultParser.php
index fa0a2672..ce6451f5 100644
--- a/src/unit/parser/ArcanistGoTestResultParser.php
+++ b/src/unit/parser/ArcanistGoTestResultParser.php
@@ -31,7 +31,7 @@ final class ArcanistGoTestResultParser extends ArcanistTestResultParser {
         // We have a passing test
         $meta = array();
         preg_match(
-          '/^--- PASS: (?P<test_name>.+) \((?P<time>.+)\s*s(?:econds)?\).*/',
+          '/^--- PASS: (?P<test_name>.+) \((?P<time>.+)\s*s(?:econds?)?\).*/',
           $line,
           $meta);
 
@@ -39,8 +39,7 @@ final class ArcanistGoTestResultParser extends ArcanistTestResultParser {
         // For now set name without test case, we'll add it later
         $result->setName($meta['test_name']);
         $result->setResult(ArcanistUnitTestResult::RESULT_PASS);
-        $result->setDuration($meta['time']);
-
+        $result->setDuration((float)$meta['time']);
         $test_case_results[] = $result;
 
         continue;
@@ -51,14 +50,14 @@ final class ArcanistGoTestResultParser extends ArcanistTestResultParser {
         $reason = trim($test_results[$i + 1]);
         $meta = array();
         preg_match(
-          '/^--- FAIL: (?P<test_name>.+) \((?P<time>.+)\s*s(?:econds)?\).*/',
+          '/^--- FAIL: (?P<test_name>.+) \((?P<time>.+)\s*s(?:econds?)?\).*/',
           $line,
           $meta);
 
         $result = new ArcanistUnitTestResult();
         $result->setName($meta['test_name']);
         $result->setResult(ArcanistUnitTestResult::RESULT_FAIL);
-        $result->setDuration($meta['time']);
+        $result->setDuration((float)$meta['time']);
         $result->setUserData($reason."\n");
 
         $test_case_results[] = $result;
@@ -85,7 +84,7 @@ final class ArcanistGoTestResultParser extends ArcanistTestResultParser {
           $result = new ArcanistUnitTestResult();
           $result->setName($test_name);
           $result->setResult(ArcanistUnitTestResult::RESULT_PASS);
-          $result->setDuration($meta['time']);
+          $result->setDuration((float)$meta['time']);
 
           $results[] = $result;
         } else {
diff --git a/src/unit/parser/ArcanistXUnitTestResultParser.php b/src/unit/parser/ArcanistXUnitTestResultParser.php
index e6c50d47..698c39d3 100644
--- a/src/unit/parser/ArcanistXUnitTestResultParser.php
+++ b/src/unit/parser/ArcanistXUnitTestResultParser.php
@@ -89,7 +89,7 @@ final class ArcanistXUnitTestResultParser extends Phobject {
       $result = new ArcanistUnitTestResult();
       $result->setName($classname.'.'.$name);
       $result->setResult($status);
-      $result->setDuration($time);
+      $result->setDuration((float)$time);
       $result->setUserData($user_data);
 
       $results[] = $result;