diff --git a/Sources/SwiftMath/MathBundle/MathFont.swift b/Sources/SwiftMath/MathBundle/MathFont.swift
index 81fc7c1..d1d501a 100644
--- a/Sources/SwiftMath/MathBundle/MathFont.swift
+++ b/Sources/SwiftMath/MathBundle/MathFont.swift
@@ -76,7 +76,9 @@ private class BundleManager {
     private var ctFonts = [CTFontSizePair: CTFont]()
     private var rawMathTables = [MathFont: NSDictionary]()
 
-    private let threadSafeQueue = DispatchQueue(label: "com.smartmath.mathfont.threadsafequeue", attributes: .concurrent)
+    private let threadSafeQueue = DispatchQueue(label: "com.smartmath.mathfont.threadsafequeue",
+                                                qos: .userInitiated,
+                                                attributes: .concurrent)
 
     private func registerCGFont(mathFont: MathFont) throws {
         guard let frameworkBundleURL = Bundle.module.url(forResource: "mathFonts", withExtension: "bundle"),
diff --git a/Sources/SwiftMath/MathRender/MTMathAtomFactory.swift b/Sources/SwiftMath/MathRender/MTMathAtomFactory.swift
index 6b79c0a..cdbde2f 100644
--- a/Sources/SwiftMath/MathRender/MTMathAtomFactory.swift
+++ b/Sources/SwiftMath/MathRender/MTMathAtomFactory.swift
@@ -62,6 +62,7 @@ public class MTMathAtomFactory {
         "rfloor" : "\u{230B}"
     ]
     
+    private static let delimValueLock = NSLock()
     static var _delimValueToName = [String: String]()
     public static var delimValueToName: [String: String] {
         if _delimValueToName.isEmpty {
@@ -78,7 +79,11 @@ public class MTMathAtomFactory {
                 }
                 output[value] = key
             }
-            _delimValueToName = output
+            delimValueLock.lock()
+            defer { delimValueLock.unlock() }
+            if _delimValueToName.isEmpty {
+                _delimValueToName = output
+            }
         }
         return _delimValueToName
     }
@@ -98,6 +103,7 @@ public class MTMathAtomFactory {
         "widetilde" :  "\u{0303}"
     ]
     
+    private static let accentValueLock = NSLock()
     static var _accentValueToName: [String: String]? = nil
     public static var accentValueToName: [String: String] {
         if _accentValueToName == nil {
@@ -115,7 +121,11 @@ public class MTMathAtomFactory {
                 }
                 output[value] = key
             }
-            _accentValueToName = output
+            accentValueLock.lock()
+            defer { accentValueLock.unlock() }
+            if _accentValueToName == nil {
+                _accentValueToName = output
+            }
         }
         return _accentValueToName!
     }
@@ -390,6 +400,7 @@ public class MTMathAtomFactory {
         "scriptscriptstyle" : MTMathStyle(style: .scriptOfScript),
     ]
     
+    private static let textToLatexLock = NSLock()
     static var _textToLatexSymbolName: [String: String]? = nil
     public static var textToLatexSymbolName: [String: String] {
         get {
@@ -413,13 +424,17 @@ public class MTMathAtomFactory {
                     }
                     output[atom.nucleus] = key
                 }
-                self._textToLatexSymbolName = output
+                textToLatexLock.lock()
+                defer { textToLatexLock.unlock() }
+                if self._textToLatexSymbolName == nil {
+                    self._textToLatexSymbolName = output
+                }
             }
             return self._textToLatexSymbolName!
         }
-        set {
-            self._textToLatexSymbolName = newValue
-        }
+        // set {
+        //     self._textToLatexSymbolName = newValue
+        // }
     }
     
   //  public static let sharedInstance = MTMathAtomFactory()
@@ -603,8 +618,13 @@ public class MTMathAtomFactory {
      e.g. to define a symbol for "lcm" one can call:
      `MTMathAtomFactory.add(latexSymbol:"lcm", value:MTMathAtomFactory.operatorWithName("lcm", limits: false))` */
     public static func add(latexSymbol name: String, value: MTMathAtom) {
+        let _ = Self.textToLatexSymbolName
+        // above force textToLatexSymbolName to instantiate first, _textToLatexSymbolName also initialized.
+        textToLatexLock.lock()
+        defer { textToLatexLock.unlock() }
         supportedLatexSymbols[name] = value
-        Self.textToLatexSymbolName[value.nucleus] = name
+        // below update the underlying dictionary entry.
+        Self._textToLatexSymbolName?[value.nucleus] = name
     }
     
     /** Returns a large opertor for the given name. If limits is true, limits are set up on
diff --git a/Sources/SwiftMath/MathRender/MTTypesetter.swift b/Sources/SwiftMath/MathRender/MTTypesetter.swift
index c766109..791c1a8 100644
--- a/Sources/SwiftMath/MathRender/MTTypesetter.swift
+++ b/Sources/SwiftMath/MathRender/MTTypesetter.swift
@@ -21,9 +21,15 @@ enum InterElementSpaceType : Int {
 }
 
 var interElementSpaceArray = [[InterElementSpaceType]]()
+private let interElementLock = NSLock()
 
 func getInterElementSpaces() -> [[InterElementSpaceType]] {
     if interElementSpaceArray.isEmpty {
+        
+        interElementLock.lock()
+        defer { interElementLock.unlock() }
+        guard interElementSpaceArray.isEmpty else { return interElementSpaceArray }
+        
         interElementSpaceArray =
         //   ordinary   operator   binary     relation  open       close     punct     fraction
         [  [.none,     .thin,     .nsMedium, .nsThick, .none,     .none,    .none,    .nsThin],    // ordinary
diff --git a/Tests/SwiftMathTests/ConcurrencyThreadsafeTests.swift b/Tests/SwiftMathTests/ConcurrencyThreadsafeTests.swift
index 3de0b64..e79f7c5 100644
--- a/Tests/SwiftMathTests/ConcurrencyThreadsafeTests.swift
+++ b/Tests/SwiftMathTests/ConcurrencyThreadsafeTests.swift
@@ -1,8 +1,47 @@
 //
-//  File.swift
+//  ConcurrencyThreadsafeTests.swift
 //  
 //
 //  Created by Peter Tang on 26/9/2023.
 //
 
-import Foundation
+import XCTest
+@testable import SwiftMath
+
+final class ConcurrencyThreadsafeTests: XCTestCase {
+    
+    private let executionQueue = DispatchQueue(label: "com.swiftmath.concurrencytests", attributes: .concurrent)
+    private let executionGroup = DispatchGroup()
+    
+    let totalCases = 20
+    var testCount = 0
+    
+    func testSwiftMathConcurrentScript() throws {
+        for caseNumber in 0 ..< totalCases {
+            helperConcurrency(caseNumber, in: executionGroup, on: executionQueue) {
+                let result1 = getInterElementSpaces()
+                let result2 = MTMathAtomFactory.delimValueToName
+                let result3 = MTMathAtomFactory.accentValueToName
+                let result4 = MTMathAtomFactory.textToLatexSymbolName
+                XCTAssertNotNil(result1)
+                XCTAssertNotNil(result2)
+                XCTAssertNotNil(result3)
+                XCTAssertNotNil(result4)
+            }
+        }
+        executionGroup.notify(queue: .main) { [weak self] in
+            // print("All test cases completed: \(self?.testCount ?? 0)")
+        }
+        executionGroup.wait()
+    }
+    func helperConcurrency(_ count: Int, in group: DispatchGroup, on queue: DispatchQueue, _ testClosure: @escaping () -> (Void)) {
+        let workitem = DispatchWorkItem {
+            testClosure()
+        }
+        workitem.notify(queue: .main) { [weak self] in
+            self?.testCount += 1
+        }
+        queue.async(group: group, execute: workitem)
+    }
+
+}