diff --git a/src/System.Management.Automation/engine/regex.cs b/src/System.Management.Automation/engine/regex.cs
index 2c467bc62d..71c6c8bac8 100644
--- a/src/System.Management.Automation/engine/regex.cs
+++ b/src/System.Management.Automation/engine/regex.cs
@@ -146,7 +146,11 @@ namespace System.Management.Automation
                 {
                     stringComparison = Options.HasFlag(WildcardOptions.CultureInvariant)
                         ? StringComparison.InvariantCultureIgnoreCase
-                        : StringComparison.CurrentCultureIgnoreCase;
+                        : CultureInfo.CurrentCulture.Name.Equals("en-US-POSIX", StringComparison.OrdinalIgnoreCase)
+                            // The collation behavior of the POSIX locale (also known as the C locale) is case sensitive.
+                            // For this specific locale, we use 'OrdinalIgnoreCase'.
+                            ? StringComparison.OrdinalIgnoreCase
+                            : StringComparison.CurrentCultureIgnoreCase;
                 }
                 else
                 {
diff --git a/test/powershell/Language/Parser/LanguageAndParser.TestFollowup.Tests.ps1 b/test/powershell/Language/Parser/LanguageAndParser.TestFollowup.Tests.ps1
index e42e06c2a4..4095477871 100644
--- a/test/powershell/Language/Parser/LanguageAndParser.TestFollowup.Tests.ps1
+++ b/test/powershell/Language/Parser/LanguageAndParser.TestFollowup.Tests.ps1
@@ -304,8 +304,8 @@ Describe "Hash expression with if statement as value" -Tags "CI" {
     }
 }
 
-Describe "Hashtable is case insensitive" -Tag CI {
-    It "When current culture is en-US-POSIX" -Skip:($IsWindows) {
+Describe "Support case-insensitive comparison in Posix locale" -Tag CI {
+    It "Hashtable is case insensitive" -Skip:($IsWindows) {
         try {
             $oldCulture = [System.Globalization.CultureInfo]::CurrentCulture
             [System.Globalization.CultureInfo]::CurrentCulture = [System.Globalization.CultureInfo]::new('en-US-POSIX')
@@ -316,4 +316,20 @@ Describe "Hashtable is case insensitive" -Tag CI {
             [System.Globalization.CultureInfo]::CurrentCulture = $oldCulture
         }
     }
+
+    It "Wildcard support case-insensitive matching" -Skip:($IsWindows) {
+        try {
+            $oldCulture = [System.Globalization.CultureInfo]::CurrentCulture
+            [System.Globalization.CultureInfo]::CurrentCulture = [System.Globalization.CultureInfo]::new('en-US-POSIX')
+
+            $wildcard1 = [WildcardPattern]::new("AbC*", [System.Management.Automation.WildcardOptions]::IgnoreCase)
+            $wildcard1.IsMatch("abcd") | Should -BeTrue
+
+            $wildcard2 = [WildcardPattern]::new("DeF", [System.Management.Automation.WildcardOptions]::IgnoreCase);
+            $wildcard2.IsMatch("def") | Should -BeTrue
+        }
+        finally {
+            [System.Globalization.CultureInfo]::CurrentCulture = $oldCulture
+        }
+    }
 }