diff --git a/PEMStoreSSH/PEMStore.cs b/PEMStoreSSH/PEMStore.cs
index d9b03e8..b8ed6b0 100644
--- a/PEMStoreSSH/PEMStore.cs
+++ b/PEMStoreSSH/PEMStore.cs
@@ -10,6 +10,7 @@
 using System.Text;
 using System.Linq;
 using System.Security.Cryptography.X509Certificates;
+using System.Threading;
 
 using PEMStoreSSH.RemoteHandlers;
 using Keyfactor.Extensions.Pam.Utilities;
@@ -21,6 +22,8 @@ internal class PEMStore
         private const string NO_EXTENSION = "noext";
         private const string FULL_SCAN = "fullscan";
 
+        static Mutex mutex = new Mutex(false, "ModifyStore");
+
         public enum FormatTypeEnum
         {
             PEM,
@@ -116,17 +119,23 @@ internal void RemoveCertificate(string alias)
         {
             try
             {
+                mutex.WaitOne();
                 CertificateHandler.RemoveCertificate(ServerType, StorePath, PrivateKeyPath, SSH, alias, String.IsNullOrEmpty(PrivateKeyPath));
             }
             catch (Exception ex)
             {
                 throw new PEMException($"Error attempting to remove certificate from store {StorePath}.", ex);
             }
+            finally
+            {
+                mutex.ReleaseMutex();
+            }
 
             if (!string.IsNullOrEmpty(PrivateKeyPath))
             {
                 try
                 {
+                    mutex.WaitOne();
                     SSH.RemoveCertificateFile(PrivateKeyPath);
                     SSH.CreateEmptyStoreFile(PrivateKeyPath);
                 }
@@ -134,6 +143,11 @@ internal void RemoveCertificate(string alias)
                 {
                     throw new PEMException($"Error attempting to remove private key {PrivateKeyPath}.", ex);
                 }
+                finally
+                {
+                    mutex.ReleaseMutex();
+                }
+
             }
         }
 
@@ -141,6 +155,7 @@ internal void AddCertificateToStore(string cert, string alias, string pfxPasswor
         {
             try
             {
+                mutex.WaitOne();
                 List<SSHFileInfo> files = CertificateHandler.CreateCertificatePacket(cert, alias, pfxPassword, storePassword, !String.IsNullOrEmpty(PrivateKeyPath));
                 CertificateHandler.AddCertificateToStore(files, StorePath, PrivateKeyPath, SSH, ServerType, overwrite, containsPrivateKey, IsSingleCertificateStore);
             }
@@ -148,6 +163,10 @@ internal void AddCertificateToStore(string cert, string alias, string pfxPasswor
             {
                 throw new PEMException($"Error attempting to add certificate to store {StorePath}.", ex);
             }
+            finally
+            {
+                mutex.ReleaseMutex();
+            }
         }
 
         internal bool IsValidStore(string path)