Make two variables unsigned to quell warnings.
diff --git a/regress/modify.c b/regress/modify.c
index bcad220..bb96e7e 100644
--- a/regress/modify.c
+++ b/regress/modify.c
@@ -71,7 +71,7 @@
 static zip_source_t *source_nul(zip_t *za, zip_uint64_t length);
 
 zip_t *za, *z_in[16];
-int z_in_count;
+unsigned int z_in_count;
 zip_flags_t stat_flags;
 
 static int
@@ -905,7 +905,8 @@
 {
     const char *archive;
     zip_source_t *memory_src;
-    int c, arg, err, flags, i;
+    unsigned int i;
+    int c, arg, err, flags;
     const char *prg;
     source_type_t source_type = SOURCE_TYPE_NONE;