diff --git a/cache.h b/cache.h
index 69801b02d5..4d8fabc6d8 100644
--- a/cache.h
+++ b/cache.h
@@ -134,6 +134,7 @@ extern const char *setup_git_directory_gently(int *);
 extern const char *setup_git_directory(void);
 extern const char *prefix_path(const char *prefix, int len, const char *path);
 extern const char *prefix_filename(const char *prefix, int len, const char *path);
+extern void verify_filename(const char *prefix, const char *name);
 
 #define alloc_nr(x) (((x)+16)*3/2)
 
diff --git a/commit-tree.c b/commit-tree.c
index e91af4bd36..bad72e89e8 100644
--- a/commit-tree.c
+++ b/commit-tree.c
@@ -45,14 +45,13 @@ static void add_buffer(char **bufp, unsigned int *sizep, const char *fmt, ...)
 
 static void check_valid(unsigned char *sha1, const char *expect)
 {
-	void *buf;
 	char type[20];
-	unsigned long size;
 
-	buf = read_sha1_file(sha1, type, &size);
-	if (!buf || strcmp(type, expect))
-		die("%s is not a valid '%s' object", sha1_to_hex(sha1), expect);
-	free(buf);
+	if (sha1_object_info(sha1, type, NULL))
+		die("%s is not a valid object", sha1_to_hex(sha1));
+	if (expect && strcmp(type, expect))
+		die("%s is not a valid '%s' object", sha1_to_hex(sha1),
+		    expect);
 }
 
 /*
diff --git a/git-rebase.sh b/git-rebase.sh
index 86dfe9cb96..f7b2b9401a 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -107,7 +107,7 @@ onto=$(git-rev-parse --verify "${onto_name}^0") || exit
 
 # Check if we are already based on $onto, but this should be
 # done only when upstream and onto are the same.
-if test "$upstream" = "onto"
+if test "$upstream" = "$onto"
 then
 	mb=$(git-merge-base "$onto" "$branch")
 	if test "$mb" = "$onto"
diff --git a/rev-parse.c b/rev-parse.c
index 7f66ae2db8..62e16af33c 100644
--- a/rev-parse.c
+++ b/rev-parse.c
@@ -160,14 +160,6 @@ static int show_file(const char *arg)
 	return 0;
 }
 
-static void die_badfile(const char *arg)
-{
-	if (errno != ENOENT)
-		die("'%s': %s", arg, strerror(errno));
-	die("'%s' is ambiguous - revision name or file/directory name?\n"
-	    "Please put '--' before the list of filenames.", arg);
-}
-
 int main(int argc, char **argv)
 {
 	int i, as_is = 0, verify = 0;
@@ -177,14 +169,12 @@ int main(int argc, char **argv)
 	git_config(git_default_config);
 
 	for (i = 1; i < argc; i++) {
-		struct stat st;
 		char *arg = argv[i];
 		char *dotdot;
 
 		if (as_is) {
 			if (show_file(arg) && as_is < 2)
-				if (lstat(arg, &st) < 0)
-					die_badfile(arg);
+				verify_filename(prefix, arg);
 			continue;
 		}
 		if (!strcmp(arg,"-n")) {
@@ -350,8 +340,7 @@ int main(int argc, char **argv)
 			continue;
 		if (verify)
 			die("Needed a single revision");
-		if (lstat(arg, &st) < 0)
-			die_badfile(arg);
+		verify_filename(prefix, arg);
 	}
 	show_default();
 	if (verify && revs_count != 1)
diff --git a/revision.c b/revision.c
index f9c7d15f56..f2a9f25fe1 100644
--- a/revision.c
+++ b/revision.c
@@ -752,17 +752,15 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 			arg++;
 		}
 		if (get_sha1(arg, sha1) < 0) {
-			struct stat st;
 			int j;
 
 			if (seen_dashdash || local_flags)
 				die("bad revision '%s'", arg);
 
 			/* If we didn't have a "--", all filenames must exist */
-			for (j = i; j < argc; j++) {
-				if (lstat(argv[j], &st) < 0)
-					die("'%s': %s", argv[j], strerror(errno));
-			}
+			for (j = i; j < argc; j++)
+				verify_filename(revs->prefix, argv[j]);
+
 			revs->prune_data = get_pathspec(revs->prefix, argv + i);
 			break;
 		}
diff --git a/setup.c b/setup.c
index 36ede3d874..cce9bb8069 100644
--- a/setup.c
+++ b/setup.c
@@ -62,6 +62,29 @@ const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
 	return path;
 }
 
+/*
+ * Verify a filename that we got as an argument for a pathspec
+ * entry. Note that a filename that begins with "-" never verifies
+ * as true, because even if such a filename were to exist, we want
+ * it to be preceded by the "--" marker (or we want the user to
+ * use a format like "./-filename")
+ */
+void verify_filename(const char *prefix, const char *arg)
+{
+	const char *name;
+	struct stat st;
+
+	if (*arg == '-')
+		die("bad flag '%s' used after filename", arg);
+	name = prefix ? prefix_filename(prefix, strlen(prefix), arg) : arg;
+	if (!lstat(name, &st))
+		return;
+	if (errno == ENOENT)
+		die("ambiguous argument '%s': unknown revision or filename\n"
+		    "Use '--' to separate filenames from revisions", arg);
+	die("'%s': %s", arg, strerror(errno));
+}
+
 const char **get_pathspec(const char *prefix, const char **pathspec)
 {
 	const char *entry = *pathspec;