diff --git a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/IncrementalManager.kt b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/IncrementalManager.kt
index d6857e3e..a6df859a 100644
--- a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/IncrementalManager.kt
+++ b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/IncrementalManager.kt
@@ -82,7 +82,8 @@ class IncrementalManager(val fileName: String = IncrementalManager.BUILD_INFO_FI
             var upToDate = false
             var taskOutputChecksum : String? = null
             inputChecksumFor(taskName)?.let { inputChecksum ->
-                if (inputChecksum == iit.inputChecksum) {
+                val dependsOnDirtyProjects = project.projectInfo.dependsOnDirtyProjects(project)
+                if (inputChecksum == iit.inputChecksum && ! dependsOnDirtyProjects) {
                     outputChecksumFor(taskName)?.let { outputChecksum ->
                         taskOutputChecksum = iit.outputChecksum()
                         if (outputChecksum == taskOutputChecksum) {
@@ -92,8 +93,13 @@ class IncrementalManager(val fileName: String = IncrementalManager.BUILD_INFO_FI
                         }
                     }
                 } else {
-                    logIncremental(2, "Incremental task $taskName input is out of date, running it"
-                            + " old: $inputChecksum new: ${iit.inputChecksum}")
+                    if (dependsOnDirtyProjects) {
+                        logIncremental(2, "Project ${project.name} depends on dirty project, running $taskName")
+                    } else {
+                        logIncremental(2, "Incremental task $taskName input is out of date, running it"
+                                + " old: $inputChecksum new: ${iit.inputChecksum}")
+                    }
+                    project.projectInfo.isDirty = true
                 }
             }
             if (! upToDate) {
diff --git a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/ProjectInfo.kt b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/ProjectInfo.kt
index c0ae052f..300be5a2 100644
--- a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/ProjectInfo.kt
+++ b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/ProjectInfo.kt
@@ -28,6 +28,13 @@ interface IProjectInfo {
      * The list of projects that this project depends on
      */
     val dependsOn: ArrayList<Project>
+
+    var isDirty: Boolean
+
+    /**
+     * @return true if any of the projects we depend on is dirty.
+     */
+    fun dependsOnDirtyProjects(project: Project) = project.projectInfo.dependsOn.any { it.projectInfo.isDirty }
 }
 
 abstract class BaseProjectInfo : IProjectInfo {
@@ -43,4 +50,6 @@ abstract class BaseProjectInfo : IProjectInfo {
             }
 
     override val dependsOn = arrayListOf<Project>()
+
+    override var isDirty = false
 }