diff --git a/Sources/SwiftDriver/ExplicitModuleBuilds/InterModuleDependencies/CommonDependencyOperations.swift b/Sources/SwiftDriver/ExplicitModuleBuilds/InterModuleDependencies/CommonDependencyOperations.swift
index 907aae1d4..ad5a41454 100644
--- a/Sources/SwiftDriver/ExplicitModuleBuilds/InterModuleDependencies/CommonDependencyOperations.swift
+++ b/Sources/SwiftDriver/ExplicitModuleBuilds/InterModuleDependencies/CommonDependencyOperations.swift
@@ -357,6 +357,15 @@ internal extension InterModuleDependencyGraph {
       return false
     }
 
+    // We do not verify the binary module itself being out-of-date if we do not have a textual
+    // interface it was built from, but we can safely treat it as up-to-date, particularly
+    // because if it is newer than any of the modules they depend on it, they will
+    // still get invalidated in the check below for whether a module has
+    // any dependencies newer than it.
+    if case .swiftPrebuiltExternal(_) = moduleID {
+      return true
+    }
+
     // Check if a dependency of this module has a newer output than this module
     for dependencyId in checkedModuleInfo.directDependencies ?? [] {
       let dependencyInfo = try moduleInfo(of: dependencyId)
@@ -400,11 +409,6 @@ internal extension InterModuleDependencyGraph {
         }
       }
     case .swiftPrebuiltExternal(_):
-      // We do not verify the binary module itself being out-of-date if we do not have a textual
-      // interface it was built from, but we can safely treat it as up-to-date, particularly
-      // because if it is newer than any of the modules they depend on it, they will
-      // still get invalidated in the check above for whether a module has
-      // any dependencies newer than it.
       return true;
     case .swiftPlaceholder(_):
       // TODO: This should never ever happen. Hard error?
diff --git a/TestInputs/ExplicitModuleBuilds/Swift/G.swiftinterface b/TestInputs/ExplicitModuleBuilds/Swift/G.swiftinterface
index 31f5140ea..f0fcd4fd9 100644
--- a/TestInputs/ExplicitModuleBuilds/Swift/G.swiftinterface
+++ b/TestInputs/ExplicitModuleBuilds/Swift/G.swiftinterface
@@ -5,3 +5,4 @@
 import Swift
 public func overlayFuncG() { }
 #endif
+import D
diff --git a/Tests/SwiftDriverTests/CachingBuildTests.swift b/Tests/SwiftDriverTests/CachingBuildTests.swift
index 936b563d1..7fa554ad2 100644
--- a/Tests/SwiftDriverTests/CachingBuildTests.swift
+++ b/Tests/SwiftDriverTests/CachingBuildTests.swift
@@ -302,6 +302,10 @@ final class CachingBuildTests: XCTestCase {
             try checkCachingBuildJob(job: job, moduleId: .clang("G"),
                                      dependencyGraph: dependencyGraph)
           }
+          else if relativeOutputPathFileName.starts(with: "D-") {
+            try checkCachingBuildJob(job: job, moduleId: .clang("D"),
+                                     dependencyGraph: dependencyGraph)
+          }
           else if relativeOutputPathFileName.starts(with: "F-") {
             try checkCachingBuildJob(job: job, moduleId: .clang("F"),
                                      dependencyGraph: dependencyGraph)
@@ -555,6 +559,10 @@ final class CachingBuildTests: XCTestCase {
             try checkCachingBuildJob(job: job, moduleId: .clang("C"),
                                      dependencyGraph: dependencyGraph)
           }
+          else if relativeOutputPathFileName.starts(with: "D-") {
+            try checkCachingBuildJob(job: job, moduleId: .clang("D"),
+                                     dependencyGraph: dependencyGraph)
+          }
           else if relativeOutputPathFileName.starts(with: "G-") {
             try checkCachingBuildJob(job: job, moduleId: .clang("G"),
                                      dependencyGraph: dependencyGraph)
@@ -775,11 +783,11 @@ final class CachingBuildTests: XCTestCase {
       let expectedNumberOfDependencies: Int
       if driver.hostTriple.isMacOSX,
          driver.hostTriple.version(for: .macOS) < Triple.Version(11, 0, 0) {
-        expectedNumberOfDependencies = 12
+        expectedNumberOfDependencies = 13
       } else if driver.targetTriple.isWindows {
-        expectedNumberOfDependencies = 14
+        expectedNumberOfDependencies = 15
       } else {
-        expectedNumberOfDependencies = 11
+        expectedNumberOfDependencies = 12
       }
 
       // Dispatch several iterations in parallel
diff --git a/Tests/SwiftDriverTests/ExplicitModuleBuildTests.swift b/Tests/SwiftDriverTests/ExplicitModuleBuildTests.swift
index 9b2cc3250..e619171a1 100644
--- a/Tests/SwiftDriverTests/ExplicitModuleBuildTests.swift
+++ b/Tests/SwiftDriverTests/ExplicitModuleBuildTests.swift
@@ -578,6 +578,10 @@ final class ExplicitModuleBuildTests: XCTestCase {
             try checkExplicitModuleBuildJob(job: job, moduleId: .clang("C"),
                                             dependencyGraph: dependencyGraph)
           }
+          else if relativeOutputPathFileName.starts(with: "D-") {
+            try checkExplicitModuleBuildJob(job: job, moduleId: .clang("D"),
+                                            dependencyGraph: dependencyGraph)
+          }
           else if relativeOutputPathFileName.starts(with: "G-") {
             try checkExplicitModuleBuildJob(job: job, moduleId: .clang("G"),
                                             dependencyGraph: dependencyGraph)
@@ -719,6 +723,10 @@ final class ExplicitModuleBuildTests: XCTestCase {
             try checkExplicitModuleBuildJob(job: job, moduleId: .clang("C"),
                                             dependencyGraph: dependencyGraph)
           }
+          else if relativeOutputPathFileName.starts(with: "D-") {
+            try checkExplicitModuleBuildJob(job: job, moduleId: .clang("D"),
+                                            dependencyGraph: dependencyGraph)
+          }
           else if relativeOutputPathFileName.starts(with: "G-") {
             try checkExplicitModuleBuildJob(job: job, moduleId: .clang("G"),
                                             dependencyGraph: dependencyGraph)
@@ -846,6 +854,10 @@ final class ExplicitModuleBuildTests: XCTestCase {
             try checkExplicitModuleBuildJob(job: job, moduleId: .clang("C"),
                                             dependencyGraph: dependencyGraph)
           }
+          else if relativeOutputPathFileName.starts(with: "D-") {
+            try checkExplicitModuleBuildJob(job: job, moduleId: .clang("D"),
+                                            dependencyGraph: dependencyGraph)
+          }
           else if relativeOutputPathFileName.starts(with: "G-") {
             try checkExplicitModuleBuildJob(job: job, moduleId: .clang("G"),
                                             dependencyGraph: dependencyGraph)
@@ -1736,11 +1748,11 @@ final class ExplicitModuleBuildTests: XCTestCase {
       let expectedNumberOfDependencies: Int
       if hostTriple.isMacOSX,
          hostTriple.version(for: .macOS) < Triple.Version(11, 0, 0) {
-        expectedNumberOfDependencies = 12
+        expectedNumberOfDependencies = 13
       } else if driver.targetTriple.isWindows {
-        expectedNumberOfDependencies = 14
+        expectedNumberOfDependencies = 15
       } else {
-        expectedNumberOfDependencies = 11
+        expectedNumberOfDependencies = 12
       }
 
       // Dispatch several iterations in parallel
diff --git a/Tests/SwiftDriverTests/IncrementalCompilationTests.swift b/Tests/SwiftDriverTests/IncrementalCompilationTests.swift
index 7d6d8a5e4..2332ccd70 100644
--- a/Tests/SwiftDriverTests/IncrementalCompilationTests.swift
+++ b/Tests/SwiftDriverTests/IncrementalCompilationTests.swift
@@ -533,10 +533,15 @@ extension IncrementalCompilationTests {
     try! localFileSystem.removeFileTree(try AbsolutePath(validating: explicitSwiftDependenciesPath.appending(component: "G.swiftinterface").pathString))
     try buildInitialState(checkDiagnostics: false, explicitModuleBuild: true)
 
-    // Touch one of the inputs to actually trigger the incremental build, so that we can ensure
-    // no module deps get re-built
+    // Touch one of the inputs to actually trigger the incremental build
     touch(inputPath(basename: "other"))
 
+    // Touch the output of a dependency of 'G', to ensure that it is newer than 'G', but 'G' still does not
+    // get "invalidated",
+    let nameOfDModule = try XCTUnwrap(modCacheEntries.first { $0.hasPrefix("D") && $0.hasSuffix(".pcm")})
+    let pathToDModule = explicitModuleCacheDir.appending(component: nameOfDModule)
+    touch(pathToDModule)
+
     try doABuild(
       "Unchanged binary dependency (G)",
       checkDiagnostics: true,
@@ -563,7 +568,6 @@ extension IncrementalCompilationTests {
       reading(deps: "other")
       schedulingPostCompileJobs
       linking
-
     }
   }
 }