diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index 232ddaab7..1312c2733 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -482,12 +482,12 @@ func (i *Image) ReadPixels(graphicsDriver graphicsdriver.Graphics, pixels []byte
 	return nil
 }
 
-// makeStaleIfDependingOn makes the image stale if the image depends on target.
-func (i *Image) makeStaleIfDependingOn(target *Image) {
+// makeStaleIfDependingOn makes the image stale if the image depends on src.
+func (i *Image) makeStaleIfDependingOn(src *Image) {
 	if i.stale {
 		return
 	}
-	if i.dependsOn(target) {
+	if i.dependsOn(src) {
 		// There is no new region to make stale.
 		i.makeStale(image.Rectangle{})
 	}
@@ -573,16 +573,14 @@ func (i *Image) resolveStale(graphicsDriver graphicsdriver.Graphics) error {
 	return i.readPixelsFromGPU(graphicsDriver)
 }
 
-// dependsOn reports whether the image depends on target.
-func (i *Image) dependsOn(target *Image) bool {
+// dependsOn reports whether the image depends on src.
+func (i *Image) dependsOn(src *Image) bool {
 	for _, c := range i.drawTrianglesHistory {
 		for _, img := range c.images {
-			if img == nil {
+			if img != src {
 				continue
 			}
-			if img == target {
-				return true
-			}
+			return true
 		}
 	}
 	return false
diff --git a/internal/restorable/images.go b/internal/restorable/images.go
index 4943c0cee..cec31dc79 100644
--- a/internal/restorable/images.go
+++ b/internal/restorable/images.go
@@ -164,16 +164,16 @@ func (i *images) resolveStaleImages(graphicsDriver graphicsdriver.Graphics) erro
 	return nil
 }
 
-// makeStaleIfDependingOn makes all the images stale that depend on target.
+// makeStaleIfDependingOn makes all the images stale that depend on src.
 //
-// When target is modified, all images depending on target can't be restored with target.
-// makeStaleIfDependingOn is called in such situation.
-func (i *images) makeStaleIfDependingOn(target *Image) {
-	if target == nil {
-		panic("restorable: target must not be nil at makeStaleIfDependingOn")
+// When src is modified, all images depending on src can't be restored with src.
+// makeStaleIfDependingOn is called in such situation.src.
+func (i *images) makeStaleIfDependingOn(src *Image) {
+	if src == nil {
+		panic("restorable: src must not be nil at makeStaleIfDependingOn")
 	}
 	for img := range i.images {
-		img.makeStaleIfDependingOn(target)
+		img.makeStaleIfDependingOn(src)
 	}
 }