diff --git a/Sources/Generator/Files/FileSystem.swift b/Sources/Generator/Files/FileSystem.swift
index 3a2656e..d571639 100644
--- a/Sources/Generator/Files/FileSystem.swift
+++ b/Sources/Generator/Files/FileSystem.swift
@@ -228,7 +228,6 @@ final class FileSystem {
     }
 
     @discardableResult
-    func requireImage(source: String, destination: String, width: Int, desiredHeight: Int? = nil)  -> NSSize {
         let height = desiredHeight.unwrapped(CGFloat.init)
         let sourceUrl = input.appendingPathComponent(source)
         let image = ImageOutput(source: source, width: width, desiredHeight: desiredHeight)
@@ -266,6 +265,7 @@ final class FileSystem {
             imageTasks[destination] = image
         }
         return scaledSize
+    func requireImage(source: String, destination: String, requiredBy path: String, width: Int, desiredHeight: Int? = nil)  -> NSSize {
     }
 
     func createImages() {
diff --git a/Sources/Generator/Generators/MarkdownProcessor.swift b/Sources/Generator/Generators/MarkdownProcessor.swift
index c9bf97d..58cd0b3 100644
--- a/Sources/Generator/Generators/MarkdownProcessor.swift
+++ b/Sources/Generator/Generators/MarkdownProcessor.swift
@@ -109,11 +109,19 @@ struct PageContentGenerator {
     private func handleImage(page: Element, file: String, rightTitle: String?, leftTitle: String?) -> String {
         let imagePath = page.pathRelativeToRootForContainedInputFile(file)
 
-        let size = files.requireImage(source: imagePath, destination: imagePath, width: configuration.pageImageWidth)
+        let size = files.requireImage(
+            source: imagePath,
+            destination: imagePath,
+            requiredBy: page.path,
+            width: configuration.pageImageWidth)
 
         let imagePath2x = imagePath.insert("@2x", beforeLast: ".")
         let file2x = file.insert("@2x", beforeLast: ".")
-        files.requireImage(source: imagePath, destination: imagePath2x, width: 2 * configuration.pageImageWidth)
+        files.requireImage(
+            source: imagePath,
+            destination: imagePath2x,
+            requiredBy: page.path,
+            width: 2 * configuration.pageImageWidth)
 
         let content: [PageImageTemplate.Key : String] = [
             .image: file,
diff --git a/Sources/Generator/Generators/PageHeadGenerator.swift b/Sources/Generator/Generators/PageHeadGenerator.swift
index ffe41ba..7495370 100644
--- a/Sources/Generator/Generators/PageHeadGenerator.swift
+++ b/Sources/Generator/Generators/PageHeadGenerator.swift
@@ -27,6 +27,7 @@ struct PageHeadGenerator {
             files.requireImage(
                 source: sourceImagePath,
                 destination: destinationImagePath,
+                requiredBy: page.path,
                 width: PageHeadGenerator.linkPreviewDesiredImageWidth)
             content[.image] =  factory.html.linkPreviewImage(file: linkPreviewImageName)
         }
diff --git a/Sources/Generator/Generators/SiteGenerator.swift b/Sources/Generator/Generators/SiteGenerator.swift
index 1acd7ae..7caba8a 100644
--- a/Sources/Generator/Generators/SiteGenerator.swift
+++ b/Sources/Generator/Generators/SiteGenerator.swift
@@ -53,6 +53,7 @@ struct SiteGenerator {
             files.requireImage(
                 source: $0.sourcePath,
                 destination: $0.destinationPath,
+                requiredBy: element.path,
                 width: $0.desiredWidth,
                 desiredHeight: $0.desiredHeight)
         }
diff --git a/Sources/Generator/Generators/ThumbnailListGenerator.swift b/Sources/Generator/Generators/ThumbnailListGenerator.swift
index d3f473a..f45f648 100644
--- a/Sources/Generator/Generators/ThumbnailListGenerator.swift
+++ b/Sources/Generator/Generators/ThumbnailListGenerator.swift
@@ -39,6 +39,7 @@ struct ThumbnailListGenerator {
         files.requireImage(
             source: fullThumbnailPath,
             destination: fullThumbnailPath,
+            requiredBy: item.path,
             width: style.width,
             desiredHeight: style.height)
 
@@ -46,6 +47,7 @@ struct ThumbnailListGenerator {
         files.requireImage(
             source: fullThumbnailPath,
             destination: fullThumbnailPath.insert("@2x", beforeLast: "."),
+            requiredBy: item.path,
             width: style.width * 2,
             desiredHeight: style.height * 2)