Ensure negation argument is signed.

diff --git a/common/image.hpp b/common/image.hpp
index ea3eefb0d589c6e3f342860b8a1bd9720b3011bf..e930512f86473c89352a8990443cd9bbff40d622 100644 (file)
--- a/common/image.hpp
+++ b/common/image.hpp
@@ -78,7 +78,7 @@ public:
     }
 
     inline signed stride(void) const {
-        return flipped ? -width*channels : width*channels;
+        return flipped ? -(signed)(width*channels) : width*channels;
     }
 
     bool writeBMP(const char *filename) const;