diff --git a/src/functions/assert/Time/Should-BeSlowerThan.ps1 b/src/functions/assert/Time/Should-BeSlowerThan.ps1
index 0d3931e73..63f98a081 100644
--- a/src/functions/assert/Time/Should-BeSlowerThan.ps1
+++ b/src/functions/assert/Time/Should-BeSlowerThan.ps1
@@ -51,7 +51,8 @@
         [Parameter(Position = 1, ValueFromPipeline = $true)]
         $Actual,
         [Parameter(Position = 0)]
-        $Expected
+        $Expected,
+        [string] $Because
     )
 
     if ($Expected -isnot [timespan]) {
diff --git a/tst/functions/assert/Time/Should-BeFasterThan.Tests.ps1 b/tst/functions/assert/Time/Should-BeFasterThan.Tests.ps1
index 085b3c569..d13b0d5b1 100644
--- a/tst/functions/assert/Time/Should-BeFasterThan.Tests.ps1
+++ b/tst/functions/assert/Time/Should-BeFasterThan.Tests.ps1
@@ -49,8 +49,9 @@ Describe "Should-BeFasterThan" {
     }
 
     It "Has Because parameter" -ForEach @(
-        @{ Actual = { Start-Sleep -Milliseconds 10 }; Expected = "1ms"; Because = "I said so" }
+        @{ Actual = [timespan]::FromMilliseconds(100); Expected = "1ms"; Because = "I said so" }
     ) {
-        { $Actual | Should-BeFasterThan -Expected $Expected -Because $Because } | Verify-AssertionFailed
+        $err = { $Actual | Should-BeFasterThan -Expected $Expected -Because $Because } | Verify-AssertionFailed
+        $err.Exception.Message | Verify-Like '*because I said so*'
     }
 }
diff --git a/tst/functions/assert/Time/Should-BeSlowerThan.Tests.ps1 b/tst/functions/assert/Time/Should-BeSlowerThan.Tests.ps1
index 79da1bb79..080265d7e 100644
--- a/tst/functions/assert/Time/Should-BeSlowerThan.Tests.ps1
+++ b/tst/functions/assert/Time/Should-BeSlowerThan.Tests.ps1
@@ -24,4 +24,11 @@ Describe "Should-BeSlowerThan" {
     ) {
         { $Actual | Should-BeSlowerThan -Expected $Expected } | Verify-AssertionFailed
     }
+
+    It "Has Because parameter" -ForEach @(
+        @{ Actual = [timespan]::FromMilliseconds(1); Expected = "1000ms"; Because = "I said so" }
+    ) {
+        $err = { $Actual | Should-BeSlowerThan -Expected $Expected -Because $Because } | Verify-AssertionFailed
+        $err.Exception.Message | Verify-Like '*because I said so*'
+    }
 }