diff --git a/meson.build b/meson.build
index 2b6e097f0..e2a0afa1d 100644
--- a/meson.build
+++ b/meson.build
@@ -1274,7 +1274,7 @@ sizet_size = cc.sizeof('size_t')
 if cc.get_id() == 'msvc' or cc.get_id() == 'clang-cl'
   ssizet_size = cc.sizeof('SSIZE_T', prefix : '#include <BaseTsd.h>')
 else
-  ssizet_size = cc.sizeof('ssize_t')
+  ssizet_size = cc.sizeof('ssize_t', prefix : '#include <unistd.h>')
 endif
 
 # Some platforms (Apple) hard-code int64_t to long long instead of