diff --git a/common/jpeg/jutils.c b/common/jpeg/jutils.c
index d18a955..98b54f5 100644
--- a/common/jpeg/jutils.c
+++ b/common/jpeg/jutils.c
@@ -77,8 +77,8 @@
 }
 
 
-GLOBAL(long)
-jround_up (long a, long b)
+GLOBAL(size_t)
+jround_up (size_t a, size_t b)
 /* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
 /* Assumes a >= 0, b > 0 */
 {