diff --git a/Source/cmake.h b/Source/cmake.h
index 7f95fb6122..c0a9b4949c 100644
--- a/Source/cmake.h
+++ b/Source/cmake.h
@@ -30,7 +30,6 @@ class cmDocumentationSection;
 class cmPolicies;
 class cmTarget;
 class cmGeneratedFileStream;
-class cmState;
 
 /** \brief Represents a cmake invocation.
  *