Add missing $

Change-Id: I13c4103750ba8f823c5b6f82a565b12414928df2
diff --git a/platforms/nexus/setup.sh b/platforms/nexus/setup.sh
index 578b466..b099047 100644
--- a/platforms/nexus/setup.sh
+++ b/platforms/nexus/setup.sh
@@ -242,7 +242,7 @@
 function nexus_load_bitstream
 {
     # Load bitstream file onto Nexus FPGA
-    local bitstream_path="$(realpath 1)"
+    local bitstream_path="$(realpath $1)"
     if [[ -z "${bitstream_path}" ]]; then
         (
             echo "Usage: nexus_load_bitstream path/to/file.bit"