diff --git a/ts_auto_deps/updater/updater.go b/ts_auto_deps/updater/updater.go
index 945420c..65d9a28 100644
--- a/ts_auto_deps/updater/updater.go
+++ b/ts_auto_deps/updater/updater.go
@@ -784,14 +784,13 @@
 // attrName from the given set of sources.
 func removeSourcesUsed(bld *build.File, ruleKind, attrName string, srcs srcSet) {
 	for _, rule := range buildRules(bld, ruleKind) {
-		ruleSrcs := rule.AttrStrings(attrName)
-		for _, s := range ruleSrcs {
+		for s, _ := range srcs {
+			pkg := filepath.Dir(bld.Path)
+			// Handles ":foo.ts" references, and concatenated lists [foo.ts] + [bar.ts]
 			// TODO(martinprobst): What to do about sources that don't seem to exist?
-			if strings.HasPrefix(s, ":") {
-				s = s[1:] // Recognize ":foo.ts" style references to sources
+			if edit.ListFind(rule.Attr(attrName), s, pkg) != nil {
+				delete(srcs, s)
 			}
-			// Might be generated srcs.
-			delete(srcs, s)
 		}
 	}
 }
diff --git a/ts_auto_deps/updater/updater_test.go b/ts_auto_deps/updater/updater_test.go
index c8d1e9b..d243ffb 100644
--- a/ts_auto_deps/updater/updater_test.go
+++ b/ts_auto_deps/updater/updater_test.go
@@ -324,6 +324,81 @@
 	}
 }
 
+func TestRemoveSourcesUsed(t *testing.T) {
+	tests := []struct {
+		name         string
+		buildFile    string
+		ruleKind     string
+		attrName     string
+		srcs         srcSet
+		expectedSrcs srcSet
+	}{
+		{
+			name:         "RemovesSources",
+			buildFile:    `ts_library(name = "lib", srcs = ["foo.ts", "bar.ts"])`,
+			ruleKind:     "ts_library",
+			attrName:     "srcs",
+			srcs:         map[string]bool{"foo.ts": true},
+			expectedSrcs: map[string]bool{},
+		},
+		{
+			name:         "WrongRuleKind",
+			buildFile:    `ts_library(name = "lib", srcs = ["foo.ts", "bar.ts"])`,
+			ruleKind:     "ng_module",
+			attrName:     "srcs",
+			srcs:         map[string]bool{"foo.ts": true},
+			expectedSrcs: map[string]bool{"foo.ts": true},
+		},
+		{
+			name:         "WrongAttrName",
+			buildFile:    `ts_library(name = "lib", srcs = ["foo.ts", "bar.ts"])`,
+			ruleKind:     "ts_library",
+			attrName:     "deps",
+			srcs:         map[string]bool{"foo.ts": true},
+			expectedSrcs: map[string]bool{"foo.ts": true},
+		},
+		{
+			name: "MultipleRules",
+			buildFile: `ts_library(name = "lib", srcs = ["foo.ts"])
+			ts_library(name = "lib2", srcs = ["bar.ts"])`,
+			ruleKind:     "ts_library",
+			attrName:     "srcs",
+			srcs:         map[string]bool{"foo.ts": true, "bar.ts": true},
+			expectedSrcs: map[string]bool{},
+		},
+		{
+			name:         "ConcatenatedLists",
+			buildFile:    `ts_library(name = "lib", srcs = ["foo.ts"] + ["bar.ts"])`,
+			ruleKind:     "ts_library",
+			attrName:     "srcs",
+			srcs:         map[string]bool{"foo.ts": true, "bar.ts": true},
+			expectedSrcs: map[string]bool{},
+		},
+		{
+			name:         "ColonReferences",
+			buildFile:    `ts_library(name = "lib", srcs = [":foo.ts", "bar.ts"])`,
+			ruleKind:     "ts_library",
+			attrName:     "srcs",
+			srcs:         map[string]bool{"foo.ts": true},
+			expectedSrcs: map[string]bool{},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			bld, err := build.ParseBuild("foo/bar/BUILD",
+				[]byte(test.buildFile))
+			if err != nil {
+				t.Fatalf("parse failure: %v", err)
+			}
+
+			removeSourcesUsed(bld, test.ruleKind, test.attrName, test.srcs)
+			if !reflect.DeepEqual(test.srcs, test.expectedSrcs) {
+				t.Errorf("expected removeSourcesUsed() = %v, expected %v", test.srcs, test.expectedSrcs)
+			}
+		})
+	}
+}
+
 func TestUpdateWebAssets(t *testing.T) {
 	ctx := context.Background()
 	bld, err := build.ParseBuild("foo/bar/BUILD",