diff --git a/cypress/integration/basics.js b/cypress/integration/basics.js
index 98ee876..613742b 100644
--- a/cypress/integration/basics.js
+++ b/cypress/integration/basics.js
@@ -1,164 +1,220 @@
 /**
  * Copyright (C) 2020  The Software Heritage developers
  * See the AUTHORS file at the top-level directory of this distribution
  * License: GNU Affero General Public License version 3, or any later version
  * See top-level LICENSE file for more information
  */
 
 /*
  * Tests the basic features of the application.
  */
 
 "use strict";
 
 describe('JSON Generation', function() {
     beforeEach(function() {
         /* Clear the session storage, as it is used to restore field data;
          * and we don't want a test to load data from the previous test. */
         cy.window().then((win) => {
             win.sessionStorage.clear()
         })
         cy.visit('./index.html');
     });
 
     it('works just from the software name', function() {
         cy.get('#name').type('My Test Software');
         cy.get('#generateCodemeta').click();
 
         cy.get('#errorMessage').should('have.text', '');
         cy.get('#codemetaText').then((elem) => JSON.parse(elem.text()))
             .should('deep.equal', {
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "SoftwareSourceCode",
                 "name": "My Test Software",
         });
     });
 
     it('works just from all main fields when using only one license', function() {
         cy.get('#name').type('My Test Software');
         cy.get('#description').type('This is a\ngreat piece of software');
         cy.get('#dateCreated').type('2019-10-02');
         cy.get('#datePublished').type('2020-01-01');
         cy.get('#license').type('AGPL-3.0');
         cy.get("#license").type('{enter}');
         cy.get('#generateCodemeta').click();
 
         cy.get("#license").should('have.value', '');
         cy.get('#errorMessage').should('have.text', '');
         cy.get('#codemetaText').then((elem) => JSON.parse(elem.text()))
             .should('deep.equal', {
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "SoftwareSourceCode",
                 "license": "https://spdx.org/licenses/AGPL-3.0",
                 "dateCreated": "2019-10-02",
                 "datePublished": "2020-01-01",
                 "name": "My Test Software",
                 "description": "This is a\ngreat piece of software",
         });
     });
 
     it('works just from all main fields when using multiple licenses', function() {
         cy.get('#name').type('My Test Software');
         cy.get('#description').type('This is a\ngreat piece of software');
         cy.get('#dateCreated').type('2019-10-02');
         cy.get('#datePublished').type('2020-01-01');
         cy.get('#license').type('AGPL-3.0');
         cy.get("#license").type('{enter}');
         cy.get('#license').type('MIT');
         cy.get("#license").type('{enter}');
 
         cy.get('#generateCodemeta').click();
 
         cy.get("#license").should('have.value', '');
         cy.get('#errorMessage').should('have.text', '');
         cy.get('#codemetaText').then((elem) => JSON.parse(elem.text()))
             .should('deep.equal', {
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "SoftwareSourceCode",
                 "license": ["https://spdx.org/licenses/AGPL-3.0", "https://spdx.org/licenses/MIT"],
                 "dateCreated": "2019-10-02",
                 "datePublished": "2020-01-01",
                 "name": "My Test Software",
                 "description": "This is a\ngreat piece of software",
         });
     });
 });
 
 describe('JSON Import', function() {
     it('works just from the software name', function() {
         cy.get('#codemetaText').then((elem) =>
             elem.text(JSON.stringify({
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "SoftwareSourceCode",
                 "name": "My Test Software",
             }))
         );
         cy.get('#importCodemeta').click();
 
         cy.get('#name').should('have.value', 'My Test Software');
     });
 
     it('works just from all main fields when using license as string', function() {
         cy.get('#codemetaText').then((elem) =>
             elem.text(JSON.stringify({
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "SoftwareSourceCode",
                 "license": "https://spdx.org/licenses/AGPL-3.0",
                 "dateCreated": "2019-10-02",
                 "datePublished": "2020-01-01",
                 "name": "My Test Software",
                 "description": "This is a\ngreat piece of software",
             }))
         );
         cy.get('#importCodemeta').click();
 
         cy.get('#name').should('have.value', 'My Test Software');
         cy.get('#description').should('have.value', 'This is a\ngreat piece of software');
         cy.get('#dateCreated').should('have.value', '2019-10-02');
         cy.get('#datePublished').should('have.value', '2020-01-01');
         cy.get('#license').should('have.value', '');
         cy.get("#selected-licenses").children().should('have.length', 1);
         cy.get("#selected-licenses").children().first().children().first().should('have.text', 'AGPL-3.0');
     });
 
     it('works just from all main fields when using license as array', function() {
         cy.get('#codemetaText').then((elem) =>
             elem.text(JSON.stringify({
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "SoftwareSourceCode",
                 "license": ["https://spdx.org/licenses/AGPL-3.0", "https://spdx.org/licenses/MIT"],
                 "dateCreated": "2019-10-02",
                 "datePublished": "2020-01-01",
                 "name": "My Test Software",
                 "description": "This is a\ngreat piece of software",
             }))
         );
         cy.get('#importCodemeta').click();
 
         cy.get('#name').should('have.value', 'My Test Software');
         cy.get('#description').should('have.value', 'This is a\ngreat piece of software');
         cy.get('#dateCreated').should('have.value', '2019-10-02');
         cy.get('#datePublished').should('have.value', '2020-01-01');
         cy.get('#license').should('have.value', '');
         cy.get("#selected-licenses").children().should('have.length', 2);
         cy.get("#selected-licenses").children().eq(0).children().first().should('have.text', 'AGPL-3.0');
         cy.get("#selected-licenses").children().eq(1).children().first().should('have.text', 'MIT');
     });
 
     it('errors on invalid type', function() {
         cy.get('#codemetaText').then((elem) =>
             elem.text(JSON.stringify({
                 "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
                 "@type": "foo",
                 "name": "My Test Software",
             }))
         );
         cy.get('#importCodemeta').click();
 
         // Should still be imported as much as possible
         cy.get('#name').should('have.value', 'My Test Software');
 
         // But must display an error
         cy.get('#errorMessage').should('have.text', 'Wrong document type: must be "SoftwareSourceCode"/"SoftwareApplication", not "foo"');
     });
+
+    it('allows singleton array as context', function() {
+        cy.get('#codemetaText').then((elem) =>
+            elem.text(JSON.stringify({
+                "@context": ["https://doi.org/10.5063/schema/codemeta-2.0"],
+                "@type": "SoftwareSourceCode",
+                "name": "My Test Software",
+            }))
+        );
+        cy.get('#importCodemeta').click();
+
+        cy.get('#name').should('have.value', 'My Test Software');
+    });
+
+    it('errors on invalid context URL', function() {
+        cy.get('#codemetaText').then((elem) =>
+            elem.text(JSON.stringify({
+                "@context": "https://doi.org/10.5063/schema/codemeta-100000",
+                "@type": "SoftwareSourceCode",
+                "name": "My Test Software",
+            }))
+        );
+        cy.get('#importCodemeta').click();
+
+        cy.get('#errorMessage').should('have.text', '@context must be "https://doi.org/10.5063/schema/codemeta-2.0", not "https://doi.org/10.5063/schema/codemeta-100000"');
+    });
+
+    it('errors on invalid context URL in array', function() {
+        cy.get('#codemetaText').then((elem) =>
+            elem.text(JSON.stringify({
+                "@context": ["https://doi.org/10.5063/schema/codemeta-100000"],
+                "@type": "SoftwareSourceCode",
+                "name": "My Test Software",
+            }))
+        );
+        cy.get('#importCodemeta').click();
+
+        cy.get('#errorMessage').should('have.text', '@context must be "https://doi.org/10.5063/schema/codemeta-2.0", not ["https://doi.org/10.5063/schema/codemeta-100000"]');
+    });
+
+    it('errors nicely when there are other contexts', function() {
+        cy.get('#codemetaText').then((elem) =>
+            elem.text(JSON.stringify({
+                "@context": [
+                    "https://doi.org/10.5063/schema/codemeta-2.0",
+                    "https://schema.org/",
+                ],
+                "@type": "SoftwareSourceCode",
+                "name": "My Test Software",
+            }))
+        );
+        cy.get('#importCodemeta').click();
+
+        cy.get('#errorMessage').should('have.text', 'Multiple values in @context are not supported (@context should be "https://doi.org/10.5063/schema/codemeta-2.0", not ["https://doi.org/10.5063/schema/codemeta-2.0","https://schema.org/"])');
+    });
+
 });
diff --git a/js/validation/index.js b/js/validation/index.js
index 6327d38..546fab0 100644
--- a/js/validation/index.js
+++ b/js/validation/index.js
@@ -1,94 +1,104 @@
 /**
  * Copyright (C) 2020  The Software Heritage developers
  * See the AUTHORS file at the top-level directory of this distribution
  * License: GNU Affero General Public License version 3, or any later version
  * See top-level LICENSE file for more information
  */
 
 /*
  * Reads a Codemeta file and shows human-friendly errors on it.
  *
  * This validator intentionaly does not use a schema, in order to show errors
  * that are easy to understand for users with no understanding of JSON-LD.
  */
 
 
 function validateDocument(doc) {
     if (!Array.isArray(doc) && typeof doc != 'object') {
         setError("Document must be an object (starting and ending with { and }), not ${typeof doc}.")
         return false;
     }
     // TODO: validate id/@id
 
+    context = doc["@context"];
+    if (context == "https://doi.org/10.5063/schema/codemeta-2.0") {
+        // Correct
+    }
+    else if (Array.isArray(context) && context.includes("https://doi.org/10.5063/schema/codemeta-2.0")) {
+        if (context.length !== 1) {
+            setError(`Multiple values in @context are not supported (@context should be "https://doi.org/10.5063/schema/codemeta-2.0", not ${JSON.stringify(context)})`);
+            return false;
+        }
+    }
+    else {
+        setError(`@context must be "https://doi.org/10.5063/schema/codemeta-2.0", not ${JSON.stringify(context)}`);
+        return false;
+    }
+
     // TODO: check there is either type or @type but not both
     var type = getDocumentType(doc);
     if (type === undefined) {
         setError("Missing type (must be SoftwareSourceCode or SoftwareApplication).")
         return false;
     }
     else if (!isCompactTypeEqual(type, "SoftwareSourceCode") && !isCompactTypeEqual(type, "SoftwareApplication")) {
         // Check this before other fields, as a wrong type error is more
         // understandable than "invalid field".
         setError(`Wrong document type: must be "SoftwareSourceCode"/"SoftwareApplication", not ${JSON.stringify(type)}`)
         return false;
     }
     else {
         return Object.entries(doc).every((entry) => {
             var fieldName = entry[0];
             var subdoc = entry[1];
             if (fieldName == "@context") {
-                if (subdoc == "https://doi.org/10.5063/schema/codemeta-2.0") {
-                    return true;
-                }
-                else {
-                    setError(`@context must be "https://doi.org/10.5063/schema/codemeta-2.0", not ${JSON.stringify(subdoc)}`);
-                    return false;
-                }
+                // Was checked before
+                return true;
             }
             else if (fieldName == "type" || fieldName == "@type") {
                 // Was checked before
                 return true;
             }
             else {
                 var validator = softwareFieldValidators[fieldName];
                 if (validator === undefined) {
                     // TODO: find if it's a field that belongs to another type,
                     // and suggest that to the user
                     setError(`Unknown field "${fieldName}".`)
                     return false;
                 }
                 else {
                     return validator(fieldName, subdoc);
                 }
             }
         });
     }
 }
 
 
 function parseAndValidateCodemeta(showPopup) {
     var codemetaText = document.querySelector('#codemetaText').innerText;
     var doc;
 
     try {
         doc = JSON.parse(codemetaText);
     }
     catch (e) {
         setError(`Could not read codemeta document because it is not valid JSON (${e}). Check for missing or extra quote, colon, or bracket characters.`);
         return;
     }
 
     setError("");
 
     var isValid = validateDocument(doc);
     if (showPopup) {
         if (isValid) {
             alert('Document is valid!')
         }
         else {
             alert('Document is invalid.');
         }
     }
 
     return doc;
 }