diff --git a/zap/src/main/java/org/parosproxy/paros/network/HttpMessage.java b/zap/src/main/java/org/parosproxy/paros/network/HttpMessage.java
index 41d71190360..4ace36efe4b 100644
--- a/zap/src/main/java/org/parosproxy/paros/network/HttpMessage.java
+++ b/zap/src/main/java/org/parosproxy/paros/network/HttpMessage.java
@@ -68,12 +68,15 @@
 import java.net.HttpCookie;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Set;
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.Vector;
@@ -156,6 +159,9 @@ public class HttpMessage implements Message {
      */
     private boolean responseFromTargetHost = false;
 
+    private static final Set<String> WARNED_CONTENT_TYPE_VALUES =
+            Collections.synchronizedSet(new HashSet<>());
+
     public HistoryReference getHistoryRef() {
         return historyRef;
     }
@@ -508,13 +514,25 @@ private static void setBodyCharset(HttpBody body, HttpHeader header) {
         if (charset != null
                 && !charset.equalsIgnoreCase(body.getCharset())
                 && !isCharsetSupported(charset)) {
-            LOGGER.warn(
-                    "Failed to set charset {} from content-type value: {}",
-                    charset,
-                    header.getNormalisedContentTypeValue());
+            String contentTypeValue = header.getNormalisedContentTypeValue();
+            if (WARNED_CONTENT_TYPE_VALUES.add(contentTypeValue)) {
+                LOGGER.warn(
+                        "Failed to set charset {} from content-type value: {}",
+                        charset,
+                        header.getNormalisedContentTypeValue());
+            }
         }
     }
 
+    /**
+     * Resets the set of warned content-type values.
+     *
+     * <p><strong>Note:</strong> Not part of the public API.
+     */
+    public static void resetWarnedContentTypeValues() {
+        WARNED_CONTENT_TYPE_VALUES.clear();
+    }
+
     private static boolean isCharsetSupported(String charset) {
         try {
             return Charset.isSupported(charset);
diff --git a/zap/src/test/java/org/parosproxy/paros/network/HttpMessageUnitTest.java b/zap/src/test/java/org/parosproxy/paros/network/HttpMessageUnitTest.java
index 151cf27e150..36dc3071fb4 100644
--- a/zap/src/test/java/org/parosproxy/paros/network/HttpMessageUnitTest.java
+++ b/zap/src/test/java/org/parosproxy/paros/network/HttpMessageUnitTest.java
@@ -21,6 +21,7 @@
 
 import static java.util.Arrays.asList;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.allOf;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
@@ -72,6 +73,7 @@ class HttpMessageUnitTest {
     @AfterEach
     void cleanUp() throws Exception {
         HttpMessage.setContentEncodingsHandler(null);
+        HttpMessage.resetWarnedContentTypeValues();
         Configurator.reconfigure(getClass().getResource("/log4j2-test.properties").toURI());
     }
 
@@ -624,6 +626,61 @@ void shouldUseDefaultAndWarnOnUnknownCharsetWhenSettingRequestBody(String charse
                 containsString("Failed to set charset"));
     }
 
+    @Test
+    void shouldWarnOnceOnSameUnknownCharsetWhenSettingRequestBody() throws Exception {
+        // Given
+        HttpMessage message = new HttpMessage();
+        message.setRequestHeader(
+                new HttpRequestHeader(
+                        "GET / HTTP/1.1\r\nContent-Type: text/plain; charset=1st_unknown"));
+        withLoggerAppender();
+        // When
+        message.setRequestBody("Body");
+        message.setRequestBody("Body");
+        message.setRequestHeader(
+                new HttpRequestHeader(
+                        "GET / HTTP/1.1\r\nContent-Type: text/plain; charset=2nd_unknown"));
+        message.setRequestBody("Body");
+        message.setRequestBody("Body");
+        // Then
+        assertThat(testAppender.getLogEvents(), hasSize(2));
+        assertThat(
+                testAppender.getLogEvents().get(0).getMessage(),
+                allOf(
+                        containsString("Failed to set charset"),
+                        containsString("charset=1st_unknown")));
+        assertThat(
+                testAppender.getLogEvents().get(1).getMessage(),
+                allOf(
+                        containsString("Failed to set charset"),
+                        containsString("charset=2nd_unknown")));
+    }
+
+    @Test
+    void shouldWarnOnceAgainOnSameUnknownCharsetWhenSettingRequestBodyAfterResettingWarns()
+            throws Exception {
+        // Given
+        HttpMessage message = new HttpMessage();
+        message.setRequestHeader(
+                new HttpRequestHeader(
+                        "GET / HTTP/1.1\r\nContent-Type: text/plain; charset=unknown"));
+        withLoggerAppender();
+        // When
+        message.setRequestBody("Body");
+        message.setRequestBody("Body");
+        HttpMessage.resetWarnedContentTypeValues();
+        message.setRequestBody("Body");
+        message.setRequestBody("Body");
+        // Then
+        assertThat(testAppender.getLogEvents(), hasSize(2));
+        assertThat(
+                testAppender.getLogEvents().get(0).getMessage(),
+                allOf(containsString("Failed to set charset"), containsString("charset=unknown")));
+        assertThat(
+                testAppender.getLogEvents().get(1).getMessage(),
+                allOf(containsString("Failed to set charset"), containsString("charset=unknown")));
+    }
+
     static Stream<Arguments> setBodyData() {
         String iso8851 = StandardCharsets.ISO_8859_1.name();
         String utf8 = StandardCharsets.UTF_8.name();
@@ -681,6 +738,61 @@ void shouldUseDefaultAndWarnOnUnknownCharsetWhenSettingResponseBody(String chars
                 containsString("Failed to set charset"));
     }
 
+    @Test
+    void shouldWarnOnceOnSameUnknownCharsetWhenSettingResponseBody() throws Exception {
+        // Given
+        HttpMessage message = new HttpMessage();
+        message.setResponseHeader(
+                new HttpResponseHeader(
+                        "HTTP/1.1 200 OK\r\nContent-Type: text/plain; charset=1st_unknown"));
+        withLoggerAppender();
+        // When
+        message.setResponseBody("Body");
+        message.setResponseBody("Body");
+        message.setResponseHeader(
+                new HttpResponseHeader(
+                        "HTTP/1.1 200 OK\r\nContent-Type: text/plain; charset=2nd_unknown"));
+        message.setResponseBody("Body");
+        message.setResponseBody("Body");
+        // Then
+        assertThat(testAppender.getLogEvents(), hasSize(2));
+        assertThat(
+                testAppender.getLogEvents().get(0).getMessage(),
+                allOf(
+                        containsString("Failed to set charset"),
+                        containsString("charset=1st_unknown")));
+        assertThat(
+                testAppender.getLogEvents().get(1).getMessage(),
+                allOf(
+                        containsString("Failed to set charset"),
+                        containsString("charset=2nd_unknown")));
+    }
+
+    @Test
+    void shouldWarnOnceAgainOnSameUnknownCharsetWhenSettingResponseBodyAfterResettingWarns()
+            throws Exception {
+        // Given
+        HttpMessage message = new HttpMessage();
+        message.setResponseHeader(
+                new HttpResponseHeader(
+                        "HTTP/1.1 200 OK\r\nContent-Type: text/plain; charset=unknown"));
+        withLoggerAppender();
+        // When
+        message.setResponseBody("Body");
+        message.setResponseBody("Body");
+        HttpMessage.resetWarnedContentTypeValues();
+        message.setResponseBody("Body");
+        message.setResponseBody("Body");
+        // Then
+        assertThat(testAppender.getLogEvents(), hasSize(2));
+        assertThat(
+                testAppender.getLogEvents().get(0).getMessage(),
+                allOf(containsString("Failed to set charset"), containsString("charset=unknown")));
+        assertThat(
+                testAppender.getLogEvents().get(1).getMessage(),
+                allOf(containsString("Failed to set charset"), containsString("charset=unknown")));
+    }
+
     private static HttpMessage newHttpMessage() throws Exception {
         HttpMessage message =
                 new HttpMessage(