diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 26b1e7614..b0caf166b 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -811,7 +811,7 @@ void cmTarget::GetDirectLinkLibraries(const char *config,
 
 //----------------------------------------------------------------------------
 void cmTarget::GetInterfaceLinkLibraries(const char *config,
-                            std::vector<std::string> &libs, cmTarget *head)
+                        std::vector<std::string> &libs, cmTarget *head) const
 {
   const char *prop = this->GetProperty("INTERFACE_LINK_LIBRARIES");
   if (prop)
diff --git a/Source/cmTarget.h b/Source/cmTarget.h
index e67edd745..aeb8703d8 100644
--- a/Source/cmTarget.h
+++ b/Source/cmTarget.h
@@ -186,7 +186,7 @@ public:
                               cmTarget const* head) const;
   void GetInterfaceLinkLibraries(const char *config,
                               std::vector<std::string> &,
-                              cmTarget *head);
+                              cmTarget *head) const;
 
   /** Compute the link type to use for the given configuration.  */
   LinkLibraryType ComputeLinkType(const char* config) const;