diff --git a/apply.c b/apply.c
index 6e0e992839..2eac3e37a9 100644
--- a/apply.c
+++ b/apply.c
@@ -93,3 +93,35 @@ void clear_apply_state(struct apply_state *state)
 
 	/* &state->fn_table is cleared at the end of apply_patch() */
 }
+
+int check_apply_state(struct apply_state *state, int force_apply)
+{
+	int is_not_gitdir = !startup_info->have_repository;
+
+	if (state->apply_with_reject && state->threeway)
+		return error("--reject and --3way cannot be used together.");
+	if (state->cached && state->threeway)
+		return error("--cached and --3way cannot be used together.");
+	if (state->threeway) {
+		if (is_not_gitdir)
+			return error(_("--3way outside a repository"));
+		state->check_index = 1;
+	}
+	if (state->apply_with_reject)
+		state->apply = state->apply_verbosely = 1;
+	if (!force_apply && (state->diffstat || state->numstat || state->summary || state->check || state->fake_ancestor))
+		state->apply = 0;
+	if (state->check_index && is_not_gitdir)
+		return error(_("--index outside a repository"));
+	if (state->cached) {
+		if (is_not_gitdir)
+			return error(_("--cached outside a repository"));
+		state->check_index = 1;
+	}
+	if (state->check_index)
+		state->unsafe_paths = 0;
+	if (!state->lock_file)
+		return error("BUG: state->lock_file should not be NULL");
+
+	return 0;
+}
diff --git a/apply.h b/apply.h
index e18a18a964..53f09b5a45 100644
--- a/apply.h
+++ b/apply.h
@@ -106,5 +106,6 @@ extern int init_apply_state(struct apply_state *state,
 			    const char *prefix,
 			    struct lock_file *lock_file);
 extern void clear_apply_state(struct apply_state *state);
+extern int check_apply_state(struct apply_state *state, int force_apply);
 
 #endif
diff --git a/builtin/apply.c b/builtin/apply.c
index bb89e07a1a..075ada47d4 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -4551,38 +4551,6 @@ static int option_parse_directory(const struct option *opt,
 	return 0;
 }
 
-static int check_apply_state(struct apply_state *state, int force_apply)
-{
-	int is_not_gitdir = !startup_info->have_repository;
-
-	if (state->apply_with_reject && state->threeway)
-		return error("--reject and --3way cannot be used together.");
-	if (state->cached && state->threeway)
-		return error("--cached and --3way cannot be used together.");
-	if (state->threeway) {
-		if (is_not_gitdir)
-			return error(_("--3way outside a repository"));
-		state->check_index = 1;
-	}
-	if (state->apply_with_reject)
-		state->apply = state->apply_verbosely = 1;
-	if (!force_apply && (state->diffstat || state->numstat || state->summary || state->check || state->fake_ancestor))
-		state->apply = 0;
-	if (state->check_index && is_not_gitdir)
-		return error(_("--index outside a repository"));
-	if (state->cached) {
-		if (is_not_gitdir)
-			return error(_("--cached outside a repository"));
-		state->check_index = 1;
-	}
-	if (state->check_index)
-		state->unsafe_paths = 0;
-	if (!state->lock_file)
-		return error("BUG: state->lock_file should not be NULL");
-
-	return 0;
-}
-
 static int apply_all_patches(struct apply_state *state,
 			     int argc,
 			     const char **argv,