diff --git a/3rdparty/libtiff/CMakeLists.txt b/3rdparty/libtiff/CMakeLists.txt
index 93bcf7ee6a..67ceac9e3f 100644
--- a/3rdparty/libtiff/CMakeLists.txt
+++ b/3rdparty/libtiff/CMakeLists.txt
@@ -11,11 +11,13 @@ check_include_file(assert.h HAVE_ASSERT_H)
 check_include_file(fcntl.h HAVE_FCNTL_H)
 check_include_file(io.h HAVE_IO_H)
 check_function_exists(jbg_newlen HAVE_JBG_NEWLEN)
-check_function_exists(mmap HAVE_MMAP)
 check_include_file(search.h HAVE_SEARCH_H)
 check_include_file(string.h HAVE_STRING_H)
 check_include_file(sys/types.h HAVE_SYS_TYPES_H)
-check_include_file(unistd.h HAVE_UNISTD_H)
+if(NOT MSVC)
+  check_include_file(unistd.h HAVE_UNISTD_H)
+  check_function_exists(mmap HAVE_MMAP)
+endif()
 
 if(WIN32 AND NOT WINRT)
   set(USE_WIN32_FILEIO 1)
diff --git a/3rdparty/zlib/CMakeLists.txt b/3rdparty/zlib/CMakeLists.txt
index 3376c3efda..84d46189a6 100644
--- a/3rdparty/zlib/CMakeLists.txt
+++ b/3rdparty/zlib/CMakeLists.txt
@@ -21,7 +21,9 @@ endif()
 #
 # Check for unistd.h
 #
-check_include_file(unistd.h Z_HAVE_UNISTD_H)
+if(NOT MSVC)
+  check_include_file(unistd.h Z_HAVE_UNISTD_H)
+endif()
 
 if(MSVC)
   add_definitions(-D_CRT_SECURE_NO_DEPRECATE)