diff --git a/common/web/types/src/kpj/keyman-developer-project.ts b/common/web/types/src/kpj/keyman-developer-project.ts
index 9ba1b299c0..ce9f78cf59 100644
--- a/common/web/types/src/kpj/keyman-developer-project.ts
+++ b/common/web/types/src/kpj/keyman-developer-project.ts
@@ -138,7 +138,7 @@ export class KeymanDeveloperProjectFile10 implements KeymanDeveloperProjectFile
     return this.callbacks.path.basename(this.filePath);
   }
   get fileType(): string {
-    return KeymanFileTypes.sourceTypeFromFilename(this.filename);
+    return KeymanFileTypes.fromFilename(this.filename);
   }
   details: KeymanDeveloperProjectFileDetail_Kmn & KeymanDeveloperProjectFileDetail_Kps; // 1.0 only
   childFiles: KeymanDeveloperProjectFile[]; // 1.0 only
@@ -156,7 +156,7 @@ export class KeymanDeveloperProjectFile20 implements KeymanDeveloperProjectFile
     return this.callbacks.path.basename(this.filePath);
   }
   get fileType() {
-    return KeymanFileTypes.sourceTypeFromFilename(this.filename);
+    return KeymanFileTypes.fromFilename(this.filename);
   }
   constructor(public readonly filePath: string, private readonly callbacks: CompilerCallbacks) {
   }
diff --git a/common/web/types/src/util/file-types.ts b/common/web/types/src/util/file-types.ts
index 230792d9b7..ebad759638 100644
--- a/common/web/types/src/util/file-types.ts
+++ b/common/web/types/src/util/file-types.ts
@@ -68,6 +68,23 @@ export type All = Source | Binary;
  */
 export type Any = string;
 
+/**
+ * Gets the file type based on extension, dealing with multi-part file
+ * extensions. Does not sniff contents of file or assume file existence. Does
+ * transform upper-cased file extensions to lower-case.
+ * @param filename
+ * @returns file extension, or `""` if no extension. Note that this return value
+ *          differs from the other, more-specific fromFilename functions below,
+ *          which return `null` if a supported extension is not found.
+ */
+export function fromFilename(filename: string): Binary | Source | Any {
+  const result =
+    sourceOrBinaryTypeFromFilename(filename) ??
+    filename.match(/\.[^\.]+$/)?.[0] ??
+    "";
+  return result;
+}
+
 /**
  * Gets the file type based on extension, dealing with multi-part file
  * extensions. Does not sniff contents of file or assume file existence.
@@ -75,7 +92,7 @@ export type Any = string;
  * @param filename
  * @returns file type, or `null` if not found
  */
-export function fromFilename(filename: string): Binary | Source {
+export function sourceOrBinaryTypeFromFilename(filename: string): Binary | Source {
   filename = filename.toLowerCase();
   const result =
     ALL_SOURCE.find(type => filename.endsWith(type)) ??