diff --git a/docs/content/v1.0.x-kor/release-notes/_index.md b/docs/content/v1.0.x-kor/release-notes/_index.md
index 7e6e4b57d..d8fc7dde9 100644
--- a/docs/content/v1.0.x-kor/release-notes/_index.md
+++ b/docs/content/v1.0.x-kor/release-notes/_index.md
@@ -5,6 +5,11 @@ menu:
 docs:
 weight: 100
 ---
+sectionStart
+### v.1.0.25
+Fix concurrency issue with string generation
+
+sectionEnd
 
 sectionStart
 ### v.1.0.24
diff --git a/docs/content/v1.0.x/release-notes/_index.md b/docs/content/v1.0.x/release-notes/_index.md
index 86af5c436..56e052aee 100644
--- a/docs/content/v1.0.x/release-notes/_index.md
+++ b/docs/content/v1.0.x/release-notes/_index.md
@@ -5,6 +5,12 @@ menu:
 docs:
 weight: 100
 ---
+sectionStart
+### v.1.0.25
+Fix concurrency issue with string generation
+
+sectionEnd
+
 sectionStart
 ### v.1.0.24
 Deprecate `ElementJsonSubTypesObjectPropertyGenerator`, `PropertyJsonSubTypesObjectPropertyGenerator` in `fixture-monkey-jackson` module.
diff --git a/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/MonkeyStringArbitrary.java b/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/MonkeyStringArbitrary.java
index e423261c9..9c88b6be6 100644
--- a/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/MonkeyStringArbitrary.java
+++ b/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/arbitrary/MonkeyStringArbitrary.java
@@ -18,6 +18,7 @@
 
 package com.navercorp.fixturemonkey.api.arbitrary;
 
+import static com.navercorp.fixturemonkey.api.jqwik.ArbitraryUtils.newThreadSafeArbitrary;
 import static java.util.Arrays.asList;
 
 import java.util.ArrayList;
@@ -71,10 +72,16 @@ public RandomGenerator<String> generator(int genSize) {
 			randomCharacterGenerator(),
 			minLength, maxLength(), maxUniqueChars,
 			genSize, lengthDistribution,
-			characterArbitrary
+			newThreadSafeArbitrary(characterArbitrary)
 		);
 	}
 
+	// Removing a StoreRepository dependency, it is not useful without Jqwik engine.
+	@Override
+	public RandomGenerator<String> generator(int genSize, boolean withEdgeCases) {
+		return this.generator(genSize);
+	}
+
 	private int maxLength() {
 		return RandomGenerators.collectionMaxSize(minLength, maxLength);
 	}
@@ -270,7 +277,6 @@ public int hashCode() {
 		return HashCodeSupport.hash(characterArbitrary, minLength, maxLength, repeatChars, filter, lengthDistribution);
 	}
 
-
 	public MonkeyStringArbitrary filterCharacter(Predicate<Character> predicate) {
 		this.filter = this.filter.and(predicate);
 		return this;
@@ -288,7 +294,6 @@ private RandomGenerator<Character> randomCharacterGenerator() {
 
 	private Arbitrary<Character> effectiveCharacterArbitrary() {
 		Arbitrary<Character> characterArbitrary = this.characterArbitrary;
-		return characterArbitrary.filter(this.filter);
+		return newThreadSafeArbitrary(characterArbitrary.filter(this.filter));
 	}
-
 }
diff --git a/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/jqwik/ArbitraryUtils.java b/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/jqwik/ArbitraryUtils.java
index 7da525520..aec39fea7 100644
--- a/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/jqwik/ArbitraryUtils.java
+++ b/fixture-monkey-api/src/main/java/com/navercorp/fixturemonkey/api/jqwik/ArbitraryUtils.java
@@ -35,27 +35,30 @@ public static <T> CombinableArbitrary<T> toCombinableArbitrary(Arbitrary<T> arbi
 		return CombinableArbitrary.from(LazyArbitrary.lazy(
 			() -> {
 				if (arbitrary != null) {
-					return new Arbitrary<T>() {
-
-						@Override
-						public RandomGenerator<T> generator(int genSize) {
-							return arbitrary.generator(genSize);
-						}
-
-						// Removing a StoreRepository dependency, it is not useful without Jqwik engine.
-						@Override
-						public RandomGenerator<T> generator(int genSize, boolean withEdgeCases) {
-							return arbitrary.generator(genSize);
-						}
-
-						@Override
-						public EdgeCases<T> edgeCases(int maxEdgeCases) {
-							return arbitrary.edgeCases(maxEdgeCases);
-						}
-					}.sample();
+					return newThreadSafeArbitrary(arbitrary).sample();
 				}
 				return null;
 			}
 		));
 	}
+
+	public static <T> Arbitrary<T> newThreadSafeArbitrary(Arbitrary<T> delegate) {
+		return new Arbitrary<T>() {
+			@Override
+			public RandomGenerator<T> generator(int genSize) {
+				return delegate.generator(genSize);
+			}
+
+			// Removing a StoreRepository dependency, it is not useful without Jqwik engine.
+			@Override
+			public RandomGenerator<T> generator(int genSize, boolean withEdgeCases) {
+				return delegate.generator(genSize);
+			}
+
+			@Override
+			public EdgeCases<T> edgeCases(int maxEdgeCases) {
+				return delegate.edgeCases(maxEdgeCases);
+			}
+		};
+	}
 }