diff --git a/Makefile b/Makefile
index a1d8775adb..ebc1a57cd4 100644
--- a/Makefile
+++ b/Makefile
@@ -642,7 +642,6 @@ PROGRAM_OBJS += http-backend.o
 PROGRAM_OBJS += imap-send.o
 PROGRAM_OBJS += sh-i18n--envsubst.o
 PROGRAM_OBJS += shell.o
-PROGRAM_OBJS += show-index.o
 PROGRAM_OBJS += upload-pack.o
 PROGRAM_OBJS += remote-testsvn.o
 
@@ -1019,6 +1018,7 @@ BUILTIN_OBJS += builtin/rm.o
 BUILTIN_OBJS += builtin/send-pack.o
 BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
+BUILTIN_OBJS += builtin/show-index.o
 BUILTIN_OBJS += builtin/show-ref.o
 BUILTIN_OBJS += builtin/stripspace.o
 BUILTIN_OBJS += builtin/submodule--helper.o
diff --git a/builtin.h b/builtin.h
index 42378f3aa4..feb559e582 100644
--- a/builtin.h
+++ b/builtin.h
@@ -218,6 +218,7 @@ extern int cmd_send_pack(int argc, const char **argv, const char *prefix);
 extern int cmd_shortlog(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
 extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
+extern int cmd_show_index(int argc, const char **argv, const char *prefix);
 extern int cmd_status(int argc, const char **argv, const char *prefix);
 extern int cmd_stripspace(int argc, const char **argv, const char *prefix);
 extern int cmd_submodule__helper(int argc, const char **argv, const char *prefix);
diff --git a/show-index.c b/builtin/show-index.c
similarity index 96%
rename from show-index.c
rename to builtin/show-index.c
index 1ead41e211..a6e678809e 100644
--- a/show-index.c
+++ b/builtin/show-index.c
@@ -1,10 +1,11 @@
+#include "builtin.h"
 #include "cache.h"
 #include "pack.h"
 
 static const char show_index_usage[] =
 "git show-index";
 
-int cmd_main(int argc, const char **argv)
+int cmd_show_index(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	unsigned nr;
diff --git a/git.c b/git.c
index ceaa58ef40..1a10c96375 100644
--- a/git.c
+++ b/git.c
@@ -464,6 +464,7 @@ static struct cmd_struct commands[] = {
 	{ "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 	{ "show", cmd_show, RUN_SETUP },
 	{ "show-branch", cmd_show_branch, RUN_SETUP },
+	{ "show-index", cmd_show_index },
 	{ "show-ref", cmd_show_ref, RUN_SETUP },
 	{ "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 	{ "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },