diff --git a/SabreTools.Serialization/Wrappers/PortableExecutable.cs b/SabreTools.Serialization/Wrappers/PortableExecutable.cs
index 3aacaab5..dc43ddb2 100644
--- a/SabreTools.Serialization/Wrappers/PortableExecutable.cs
+++ b/SabreTools.Serialization/Wrappers/PortableExecutable.cs
@@ -850,47 +850,50 @@ namespace SabreTools.Serialization.Wrappers
             if (string.IsNullOrEmpty(key))
                 return null;
 
-            // If we have the value cached
-            if (_versionInfoStrings.ContainsKey(key))
-                return _versionInfoStrings[key];
-
-            // Ensure that we have the resource data cached
-            if (ResourceData == null)
-                return null;
-
-            // If we don't have string version info in this executable
-            var stringTable = _versionInfo?.StringFileInfo?.Children;
-            if (stringTable == null || stringTable.Length == 0)
-                return null;
-
-            // Try to find a key that matches
-#if NET20
-            Models.PortableExecutable.StringData? match = null;
-            foreach (var st in stringTable)
+            lock (_sourceDataLock)
             {
-                if (st?.Children == null)
-                    continue;
-
-                // Return the match if found
-                match = Array.Find(st.Children, sd => sd != null && key.Equals(sd.Key, StringComparison.OrdinalIgnoreCase));
-                if (match != null)
-                {
-                    _versionInfoStrings[key] = match.Value?.TrimEnd('\0');
+                // If we have the value cached
+                if (_versionInfoStrings.ContainsKey(key))
                     return _versionInfoStrings[key];
+
+                // Ensure that we have the resource data cached
+                if (ResourceData == null)
+                    return null;
+
+                // If we don't have string version info in this executable
+                var stringTable = _versionInfo?.StringFileInfo?.Children;
+                if (stringTable == null || stringTable.Length == 0)
+                    return null;
+
+                // Try to find a key that matches
+#if NET20
+                Models.PortableExecutable.StringData? match = null;
+                foreach (var st in stringTable)
+                {
+                    if (st?.Children == null)
+                        continue;
+
+                    // Return the match if found
+                    match = Array.Find(st.Children, sd => sd != null && key.Equals(sd.Key, StringComparison.OrdinalIgnoreCase));
+                    if (match != null)
+                    {
+                        _versionInfoStrings[key] = match.Value?.TrimEnd('\0');
+                        return _versionInfoStrings[key];
+                    }
                 }
-            }
 
-            _versionInfoStrings[key] = null;
-            return _versionInfoStrings[key];
+                _versionInfoStrings[key] = null;
+                return _versionInfoStrings[key];
 #else
-            var match = stringTable
-                .SelectMany(st => st?.Children ?? [])
-                .FirstOrDefault(sd => sd != null && key.Equals(sd.Key, StringComparison.OrdinalIgnoreCase));
+                var match = stringTable
+                    .SelectMany(st => st?.Children ?? [])
+                    .FirstOrDefault(sd => sd != null && key.Equals(sd.Key, StringComparison.OrdinalIgnoreCase));
 
-            // Return either the match or null
-            _versionInfoStrings[key] = match?.Value?.TrimEnd('\0');
-            return _versionInfoStrings[key];
+                // Return either the match or null
+                _versionInfoStrings[key] = match?.Value?.TrimEnd('\0');
+                return _versionInfoStrings[key];
 #endif
+            }
         }
 
         /// <summary>