diff --git a/diff-lib.c b/diff-lib.c
index 23c8d351b3..a838c219ec 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -531,7 +531,7 @@ int run_diff_index(struct rev_info *revs, int cached)
 		exit(128);
 
 	diff_set_mnemonic_prefix(&revs->diffopt, "c/", cached ? "i/" : "w/");
-	diffcore_fix_diff_index(&revs->diffopt);
+	diffcore_fix_diff_index();
 	diffcore_std(&revs->diffopt);
 	diff_flush(&revs->diffopt);
 	trace_performance_leave("diff-index");
diff --git a/diff.c b/diff.c
index 5306c48652..3e7d11fb70 100644
--- a/diff.c
+++ b/diff.c
@@ -6224,7 +6224,7 @@ static int diffnamecmp(const void *a_, const void *b_)
 	return strcmp(name_a, name_b);
 }
 
-void diffcore_fix_diff_index(struct diff_options *options)
+void diffcore_fix_diff_index(void)
 {
 	struct diff_queue_struct *q = &diff_queued_diff;
 	QSORT(q->queue, q->nr, diffnamecmp);
diff --git a/diff.h b/diff.h
index b512d0477a..8f55aad5ba 100644
--- a/diff.h
+++ b/diff.h
@@ -367,7 +367,7 @@ int git_config_rename(const char *var, const char *value);
 #define DIFF_PICKAXE_IGNORE_CASE	32
 
 void diffcore_std(struct diff_options *);
-void diffcore_fix_diff_index(struct diff_options *);
+void diffcore_fix_diff_index(void);
 
 #define COMMON_DIFF_OPTIONS_HELP \
 "\ncommon diff options:\n" \