diff --git a/lib/jpegli/common_internal.h b/lib/jpegli/common_internal.h
index a5e559d5..a5da3ef4 100644
--- a/lib/jpegli/common_internal.h
+++ b/lib/jpegli/common_internal.h
@@ -31,6 +31,7 @@
 
 #include <hwy/aligned_allocator.h>
 
+#include "lib/base/compiler_specific.h"  // for ssize_t
 #include "lib/jpegli/memory_manager.h"
 #include "lib/jpegli/simd.h"