diff --git a/docs-core/src/test/java/com/sismics/util/format/TestPdfFormatHandler.java b/docs-core/src/test/java/com/sismics/util/format/TestPdfFormatHandler.java
index 7b664df7..7e3b2f00 100644
--- a/docs-core/src/test/java/com/sismics/util/format/TestPdfFormatHandler.java
+++ b/docs-core/src/test/java/com/sismics/util/format/TestPdfFormatHandler.java
@@ -6,7 +6,15 @@ import org.junit.Test;
 
 import java.nio.file.Paths;
 
+/**
+ * Test of {@link PdfFormatHandler}
+ *
+ * @author bgamard
+ */
 public class TestPdfFormatHandler {
+    /**
+     * Test related to https://github.com/sismics/docs/issues/373.
+     */
     @Test
     public void testIssue373() throws Exception {
         PdfFormatHandler formatHandler = new PdfFormatHandler();
diff --git a/docs-web-common/src/main/java/com/sismics/rest/util/ValidationUtil.java b/docs-web-common/src/main/java/com/sismics/rest/util/ValidationUtil.java
index ce4b9883..c2054043 100644
--- a/docs-web-common/src/main/java/com/sismics/rest/util/ValidationUtil.java
+++ b/docs-web-common/src/main/java/com/sismics/rest/util/ValidationUtil.java
@@ -111,7 +111,18 @@ public class ValidationUtil {
     public static void validateHexColor(String s, String name, boolean nullable) throws ClientException {
         ValidationUtil.validateLength(s, name, 7, 7, nullable);
     }
-    
+
+    /**
+     * Validate a tag name.
+     *
+     * @param name Name of the tag
+     */
+    public static void validateTagName(String name) throws ClientException {
+        if (name.contains(" ") || name.contains(":")) {
+            throw new ClientException("IllegalTagName", "Spaces and colons are not allowed in tag name");
+        }
+    }
+
     /**
      * Validates that the provided string matches an URL with HTTP or HTTPS scheme.
      * 
diff --git a/docs-web/src/main/java/com/sismics/docs/rest/resource/TagResource.java b/docs-web/src/main/java/com/sismics/docs/rest/resource/TagResource.java
index 731e6307..92485097 100644
--- a/docs-web/src/main/java/com/sismics/docs/rest/resource/TagResource.java
+++ b/docs-web/src/main/java/com/sismics/docs/rest/resource/TagResource.java
@@ -155,7 +155,7 @@ public class TagResource extends BaseResource {
      * @apiSuccess {String} id Tag ID
      * @apiError (client) ForbiddenError Access denied
      * @apiError (client) ValidationError Validation error
-     * @apiError (client) SpacesNotAllowed Spaces are not allowed in tag name
+     * @apiError (client) IllegalTagName Spaces and colons are not allowed in tag name
      * @apiError (client) ParentNotFound Parent not found
      * @apiPermission user
      * @apiVersion 1.5.0
@@ -177,12 +177,8 @@ public class TagResource extends BaseResource {
         // Validate input data
         name = ValidationUtil.validateLength(name, "name", 1, 36, false);
         ValidationUtil.validateHexColor(color, "color", true);
-        
-        // Don't allow spaces
-        if (name.contains(" ")) {
-            throw new ClientException("SpacesNotAllowed", "Spaces are not allowed in tag name");
-        }
-        
+        ValidationUtil.validateTagName(name);
+
         // Check the parent
         if (StringUtils.isEmpty(parentId)) {
             parentId = null;
@@ -237,7 +233,7 @@ public class TagResource extends BaseResource {
      * @apiSuccess {String} id Tag ID
      * @apiError (client) ForbiddenError Access denied
      * @apiError (client) ValidationError Validation error
-     * @apiError (client) SpacesNotAllowed Spaces are not allowed in tag name
+     * @apiError (client) IllegalTagName Spaces and colons are not allowed in tag name
      * @apiError (client) ParentNotFound Parent not found
      * @apiError (client) CircularReference Circular reference in parent tag
      * @apiError (client) NotFound Tag not found
@@ -263,12 +259,8 @@ public class TagResource extends BaseResource {
         // Validate input data
         name = ValidationUtil.validateLength(name, "name", 1, 36, true);
         ValidationUtil.validateHexColor(color, "color", true);
-        
-        // Don't allow spaces
-        if (name.contains(" ")) {
-            throw new ClientException("SpacesNotAllowed", "Spaces are not allowed in tag name");
-        }
-        
+        ValidationUtil.validateTagName(name);
+
         // Check permission
         AclDao aclDao = new AclDao();
         if (!aclDao.checkPermission(id, PermType.WRITE, getTargetIdList(null))) {
diff --git a/docs-web/src/test/java/com/sismics/docs/rest/TestTagResource.java b/docs-web/src/test/java/com/sismics/docs/rest/TestTagResource.java
index b8f4b5fa..bf98a570 100644
--- a/docs-web/src/test/java/com/sismics/docs/rest/TestTagResource.java
+++ b/docs-web/src/test/java/com/sismics/docs/rest/TestTagResource.java
@@ -25,7 +25,23 @@ public class TestTagResource extends BaseJerseyTest {
         // Login tag1
         clientUtil.createUser("tag1");
         String tag1Token = clientUtil.login("tag1");
-        
+
+        // Create a tag with a wrong name
+        Response response = target().path("/tag").request()
+                .cookie(TokenBasedSecurityFilter.COOKIE_NAME, tag1Token)
+                .put(Entity.form(new Form()
+                        .param("name", "Tag:3")
+                        .param("color", "#ff0000")));
+        Assert.assertEquals(Status.BAD_REQUEST, Status.fromStatusCode(response.getStatus()));
+
+        // Create a tag with a wrong name
+        response = target().path("/tag").request()
+                .cookie(TokenBasedSecurityFilter.COOKIE_NAME, tag1Token)
+                .put(Entity.form(new Form()
+                        .param("name", "Tag 3")
+                        .param("color", "#ff0000")));
+        Assert.assertEquals(Status.BAD_REQUEST, Status.fromStatusCode(response.getStatus()));
+
         // Create a tag
         JsonObject json = target().path("/tag").request()
                 .cookie(TokenBasedSecurityFilter.COOKIE_NAME, tag1Token)
@@ -46,7 +62,7 @@ public class TestTagResource extends BaseJerseyTest {
         Assert.assertNotNull(tag4Id);
 
         // Create a circular reference
-        Response response = target().path("/tag/" + tag3Id).request()
+        response = target().path("/tag/" + tag3Id).request()
                 .cookie(TokenBasedSecurityFilter.COOKIE_NAME, tag1Token)
                 .post(Entity.form(new Form()
                         .param("name", "Tag3")