diff --git a/spring-restdocs-mockmvc/src/main/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverter.java b/spring-restdocs-mockmvc/src/main/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverter.java
index e8ddd1e8..0fe60b79 100644
--- a/spring-restdocs-mockmvc/src/main/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverter.java
+++ b/spring-restdocs-mockmvc/src/main/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverter.java
@@ -284,7 +284,7 @@ private static void processParameter(String parameter, MultiValueMap<String, Str
 	}
 
 	private static String decode(String encoded) {
-		return URLDecoder.decode(encoded, StandardCharsets.US_ASCII);
+		return URLDecoder.decode(encoded, StandardCharsets.UTF_8);
 	}
 
 }
diff --git a/spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverterTests.java b/spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverterTests.java
index 7a88b067..7b384c0e 100644
--- a/spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverterTests.java
+++ b/spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverterTests.java
@@ -160,6 +160,19 @@ void postRequestWithParametersAndQueryStringCreatesFormUrlEncodedContentWithoutD
 		assertThat(request.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_FORM_URLENCODED);
 	}
 
+	@Test
+	void postRequestWithNonAsciiParametersAndQueryStringCreatesFormUrlEncodedContentWithoutDuplication() {
+		OperationRequest request = createOperationRequest(MockMvcRequestBuilders
+			.post("/foo?name=%ED%99%8D%EA%B8%B8%EB%8F%99")
+			.param("name", "\uD64D\uAE38\uB3D9")
+			.param("other", "\uD64D\uAE38\uB3D9"));
+		assertThat(request.getUri())
+			.isEqualTo(URI.create("http://localhost/foo?name=%ED%99%8D%EA%B8%B8%EB%8F%99"));
+		assertThat(request.getMethod()).isEqualTo(HttpMethod.POST);
+		assertThat(request.getContentAsString()).isEqualTo("other=%ED%99%8D%EA%B8%B8%EB%8F%99");
+		assertThat(request.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_FORM_URLENCODED);
+	}
+
 	@Test
 	void mockMultipartFileUpload() {
 		OperationRequest request = createOperationRequest(MockMvcRequestBuilders.multipart("/foo")