diff --git a/src/worn.c b/src/worn.c
index 96c611731..96dd00c6c 100644
--- a/src/worn.c
+++ b/src/worn.c
@@ -147,7 +147,7 @@ int adjust;	/* positive => increase speed, negative => decrease */
 {
     struct obj *otmp;
 
-    int oldspeed = mon->mspeed;
+    unsigned int oldspeed = mon->mspeed;
 
     switch (adjust) {
      case  2: