diff --git a/build-exosphere.sh b/build-exosphere.sh
index 1a2f557d..c7d6340f 100755
--- a/build-exosphere.sh
+++ b/build-exosphere.sh
@@ -41,9 +41,25 @@ cp -v "$EXO_SRC/secmon_memory_layout.hpp"               "$LIBEXO_DEST/"
 echo
 echo "*** Compiling exosphere ***"
 cd "$ATMOSPHERE_DIR/exosphere" || exit 1
-make -j"$CORES"
+
+# .d files store absolute source paths. If this checkout moved (e.g. renamed
+# Horizon-OC -> Horizon-OC-pro), those deps point at a dead tree and make fails.
+if grep -Rql --include='*.d' '/Desktop/Horizon-OC/' "$ATMOSPHERE_DIR" 2>/dev/null; then
+    echo "*** Cleaning stale build deps (old Horizon-OC absolute paths) ***"
+    make clean || true
+fi
+
+make -j"$CORES" || {
+    echo "*** Build failed ***" >&2
+    exit 1
+}
 cd "$ROOT_DIR" || exit 1
 
+if [ ! -f "$EXO_OUT" ]; then
+    echo "*** Missing output: $EXO_OUT ***" >&2
+    exit 1
+fi
+
 mkdir -p "$DIST_DIR/atmosphere"
 cp -v "$EXO_OUT" "$DIST_DIR/atmosphere/exosphere.bin"