diff --git a/xdiff-interface.c b/xdiff-interface.c
index 01f14fb50f..b78f757193 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -211,8 +211,10 @@ int read_mmfile(mmfile_t *ptr, const char *filename)
 		return error("Could not open %s", filename);
 	sz = xsize_t(st.st_size);
 	ptr->ptr = xmalloc(sz ? sz : 1);
-	if (sz && fread(ptr->ptr, sz, 1, f) != 1)
+	if (sz && fread(ptr->ptr, sz, 1, f) != 1) {
+		fclose(f);
 		return error("Could not read %s", filename);
+	}
 	fclose(f);
 	ptr->size = sz;
 	return 0;