diff --git a/thirdparty/libtiff/CMakeLists.txt b/thirdparty/libtiff/CMakeLists.txt
index 8a4622638..b1441d006 100644
--- a/thirdparty/libtiff/CMakeLists.txt
+++ b/thirdparty/libtiff/CMakeLists.txt
@@ -221,6 +221,7 @@ else()
       message(FATAL_ERROR "unknown ssize_t")
     endif()
   else()
+    set(TIFF_SSIZE_FORMAT "%ld")
     set(TIFF_SSIZE_T   ssize_t)
   endif()
   set(TIFF_INT32_FORMAT "%d")