diff --git a/CMakeLists.txt b/CMakeLists.txt
index dee9d44..b85ef76 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.10)
-project(pmm VERSION 1.5.1)
+project(pmm VERSION 1.6.0)
 
 set(PMM_ALWAYS_DOWNLOAD TRUE)
 set(PMM_URL "file://${PROJECT_SOURCE_DIR}/pmm")
diff --git a/changelog.cmake b/changelog.cmake
index 6fd81e9..b6950c1 100644
--- a/changelog.cmake
+++ b/changelog.cmake
@@ -103,6 +103,9 @@ _pmm_changes(1.5.1
         "Fix: Unable to run in script mode due to define_property() calls"
         "Fix: Generated Conan profiles without respecting the CMAKE_BUILD_TYPE"
         )
+_pmm_changes(1.6.0
+        "New: add OVERLAY_PORTS and OVERLAY_TRIPLETS to pmm(VCPKG)"
+        )
 message(STATUS "[pmm] To update, simply change the value of PMM_VERSION_INIT in pmm.cmake")
 message(STATUS "[pmm] You can disable these messages by setting PMM_IGNORE_NEW_VERSION to TRUE before including pmm.cmake")
 
diff --git a/conanfile.py b/conanfile.py
index 3b6d373..f617d4d 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -3,7 +3,7 @@
 
 class PMM(conans.ConanFile):
     name = 'pmm'
-    version = '1.5.1'
+    version = '1.6.0'
     settings = None
     exports_sources = '*'
     generators = 'cmake'
diff --git a/latest-version.cmake b/latest-version.cmake
index da25555..e192c13 100644
--- a/latest-version.cmake
+++ b/latest-version.cmake
@@ -1 +1 @@
-set(PMM_LATEST_VERSION 1.5.1)
\ No newline at end of file
+set(PMM_LATEST_VERSION 1.6.0)
\ No newline at end of file
diff --git a/pmm.cmake b/pmm.cmake
index e341399..894efc1 100644
--- a/pmm.cmake
+++ b/pmm.cmake
@@ -21,11 +21,11 @@
 ## SOFTWARE.
 
 # Bump this version to change what PMM version is downloaded
-set(PMM_VERSION_INIT 1.5.1)
+set(PMM_VERSION_INIT 1.6.0)
 
 # Helpful macro to set a variable if it isn't already set
 macro(_pmm_set_if_undef varname)
-    if(NOT DEFINED "${varname}")
+    if(NOT DEFINED ${varname})
         set("${varname}" "${ARGN}")
     endif()
 endmacro()
diff --git a/pmm/vcpkg.cmake b/pmm/vcpkg.cmake
index 6a4c33e..bc37ed4 100644
--- a/pmm/vcpkg.cmake
+++ b/pmm/vcpkg.cmake
@@ -181,7 +181,7 @@ endfunction()
 function(_pmm_vcpkg)
     _pmm_parse_args(
         - REVISION TRIPLET
-        + REQUIRES PORTS
+        + REQUIRES PORTS OVERLAY_PORTS OVERLAY_TRIPLETS
         )
 
     if(NOT DEFINED ARG_REVISION)
@@ -202,6 +202,13 @@ function(_pmm_vcpkg)
         _pmm_vcpkg_copy_custom_ports("${ARG_PORTS}")
     endif()
     if(ARG_REQUIRES)
+        list(APPEND _PMM_OVERLAYS)
+        if(ARG_OVERLAY_PORTS)
+            list(APPEND _PMM_OVERLAYS "--overlay-ports=${ARG_OVERLAY_PORTS}")
+        endif()
+        if(ARG_OVERLAY_TRIPLETS)
+            list(APPEND _PMM_OVERLAYS "--overlay-triplets=${ARG_OVERLAY_TRIPLETS}")
+        endif()
         _pmm_log("Installing requirements with vcpkg")
         set(cmd ${CMAKE_COMMAND} -E env
                 VCPKG_ROOT=${vcpkg_inst_dir}
@@ -210,6 +217,7 @@ function(_pmm_vcpkg)
             "${PMM_VCPKG_EXECUTABLE}" install
                 --triplet "${ARG_TRIPLET}"
                 ${ARG_REQUIRES}
+                ${_PMM_OVERLAYS}
             )
         _pmm_exec(${cmd} NO_EAT_OUTPUT)
         if(_PMM_RC)
@@ -218,6 +226,12 @@ function(_pmm_vcpkg)
             _pmm_log(DEBUG "vcpkg output:\n${_PMM_OUTPUT}")
         endif()
     endif()
-    set(_PMM_INCLUDE "${vcpkg_inst_dir}/scripts/buildsystems/vcpkg.cmake" PARENT_SCOPE)
-    _pmm_generate_shim(vcpkg "${PMM_VCPKG_EXECUTABLE}")
+    get_property(__pmm_vcpkg_included GLOBAL PROPERTY pmm_VCPKG_INCLUDED)
+    if(NOT __pmm_vcpkg_included)
+        set_property(GLOBAL PROPERTY pmm_VCPKG_INCLUDED TRUE)
+        set(_PMM_INCLUDE "${vcpkg_inst_dir}/scripts/buildsystems/vcpkg.cmake" PARENT_SCOPE)
+        _pmm_generate_shim(vcpkg "${PMM_VCPKG_EXECUTABLE}")
+    else()
+        set(_PMM_INCLUDE "" PARENT_SCOPE)
+    endif()
 endfunction()