diff --git a/configure/src/core/utils.js b/configure/src/core/utils.js
index 12f7d8fbe1..e9fd6684f8 100644
--- a/configure/src/core/utils.js
+++ b/configure/src/core/utils.js
@@ -6,7 +6,8 @@ export const isNumeric = (value) => {
 };
 
 export const isUrlAbsolute = (url) => {
-  const r = new RegExp("^(?:[a-z]+:)?//", "i");
+  // RFC 3986 scheme (letters, digits, + - .) so s3://, gs://, etc. count
+  const r = new RegExp("^(?:[a-z][a-z0-9+.-]*:)?//", "i");
   return r.test(url);
 };
 
diff --git a/src/essence/Basics/Formulae_/Formulae_.js b/src/essence/Basics/Formulae_/Formulae_.js
index 56cbdecab4..ebb77980f6 100644
--- a/src/essence/Basics/Formulae_/Formulae_.js
+++ b/src/essence/Basics/Formulae_/Formulae_.js
@@ -822,7 +822,8 @@ var Formulae_ = {
         return 'zero'
     },
     isUrlAbsolute: function (url) {
-        const r = new RegExp('^(?:[a-z]+:)?//', 'i')
+        // RFC 3986 scheme (letters, digits, + - .) so s3://, gs://, etc. count
+        const r = new RegExp('^(?:[a-z][a-z0-9+.-]*:)?//', 'i')
         return r.test(url)
     },
     csvToJSON: function (csv) {
diff --git a/tests/unit/formulae.spec.js b/tests/unit/formulae.spec.js
index 8982390408..d529f51d86 100644
--- a/tests/unit/formulae.spec.js
+++ b/tests/unit/formulae.spec.js
@@ -851,6 +851,15 @@ test.describe('Formulae_ - Validation Utilities', () => {
     test('detects absolute URLs', () => {
       expect(F_.isUrlAbsolute('http://example.com')).toBe(true);
       expect(F_.isUrlAbsolute('https://example.com')).toBe(true);
+      expect(F_.isUrlAbsolute('//example.com/path')).toBe(true);
+    });
+
+    test('detects schemes containing digits or punctuation', () => {
+      expect(F_.isUrlAbsolute('s3://my-bucket/path/file.tif')).toBe(true);
+      expect(F_.isUrlAbsolute('gs://my-bucket/file.tif')).toBe(true);
+      expect(F_.isUrlAbsolute('az://container/file.tif')).toBe(true);
+      expect(F_.isUrlAbsolute('file:///Missions/cog.tif')).toBe(true);
+      expect(F_.isUrlAbsolute('svn+ssh://host/repo')).toBe(true);
     });
 
     test('detects relative URLs', () => {