diff --git a/ChangeLog b/ChangeLog
index 329f973d16..d92ba09d67 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+Mon May 17 22:19:16 2010  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* process.c: suppress warning for signed and unsigned type
+	  inconsistency.
+
+	* ext/psych/parser.c: ditto.
+
+	* ext/sdbm/_sdbm.c: ditto.
+
+	* ext/syck/rubyext.c: ditto.
+
 Mon May 17 21:30:50 2010  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* .gitignore: updated.
diff --git a/ext/psych/parser.c b/ext/psych/parser.c
index 0fa02b981f..eefb8e67bc 100644
--- a/ext/psych/parser.c
+++ b/ext/psych/parser.c
@@ -55,7 +55,7 @@ static VALUE parse(VALUE self, VALUE yaml)
     int done = 0;
 #ifdef HAVE_RUBY_ENCODING_H
     int encoding = rb_enc_find_index("ASCII-8BIT");
-    rb_encoding * internal_enc;
+    rb_encoding * internal_enc = 0;
 #endif
     VALUE handler = rb_iv_get(self, "@handler");
 
diff --git a/ext/sdbm/_sdbm.c b/ext/sdbm/_sdbm.c
index b1ffdc04f0..0df95ece8f 100644
--- a/ext/sdbm/_sdbm.c
+++ b/ext/sdbm/_sdbm.c
@@ -861,7 +861,7 @@ chkpage(char *pag)
 	register int off;
 	register short *ino = (short *) pag;
 
-	if ((n = GET_SHORT(ino,0)) < 0 || n > PBLKSIZ / sizeof(short))
+	if ((n = GET_SHORT(ino,0)) < 0 || n > PBLKSIZ / (int)sizeof(short))
 		return 0;
 
 	if (n > 0) {
diff --git a/ext/syck/rubyext.c b/ext/syck/rubyext.c
index af52976ff1..cd5b4f2049 100644
--- a/ext/syck/rubyext.c
+++ b/ext/syck/rubyext.c
@@ -275,7 +275,7 @@ mktime_do(struct mktime_arg *arg)
         char *end = ptr + 1;
         char *p = end;
         while ( isdigit( *end ) ) end++;
-        if (end - p < sizeof(padded)) {
+        if (end - p < (int)sizeof(padded)) {
             MEMCPY(padded, ptr + 1, char, end - (ptr + 1));
             p = padded;
         }
diff --git a/process.c b/process.c
index 073b380f74..3145f617fc 100644
--- a/process.c
+++ b/process.c
@@ -4093,9 +4093,9 @@ p_uid_change_privilege(VALUE obj, VALUE id)
 #endif
     } else { /* unprivileged user */
 #if defined(HAVE_SETRESUID)
-	if (setresuid((getuid() == uid)? -1: uid,
-		      (geteuid() == uid)? -1: uid,
-		      (SAVED_USER_ID == uid)? -1: uid) < 0) rb_sys_fail(0);
+	if (setresuid((getuid() == uid)? (rb_uid_t)-1: uid,
+		      (geteuid() == uid)? (rb_uid_t)-1: uid,
+		      (SAVED_USER_ID == uid)? (rb_uid_t)-1: uid) < 0) rb_sys_fail(0);
 	SAVED_USER_ID = uid;
 #elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
 	if (SAVED_USER_ID == uid) {
@@ -4712,9 +4712,9 @@ p_gid_change_privilege(VALUE obj, VALUE id)
 #endif
     } else { /* unprivileged user */
 #if defined(HAVE_SETRESGID)
-	if (setresgid((getgid() == gid)? -1: gid,
-		      (getegid() == gid)? -1: gid,
-		      (SAVED_GROUP_ID == gid)? -1: gid) < 0) rb_sys_fail(0);
+	if (setresgid((getgid() == gid)? (rb_gid_t)-1: gid,
+		      (getegid() == gid)? (rb_gid_t)-1: gid,
+		      (SAVED_GROUP_ID == gid)? (rb_gid_t)-1: gid) < 0) rb_sys_fail(0);
 	SAVED_GROUP_ID = gid;
 #elif defined(HAVE_SETREGID) && !defined(OBSOLETE_SETREGID)
 	if (SAVED_GROUP_ID == gid) {