diff --git a/.gitignore b/.gitignore
new file mode 100644
index 000000000..50e96a8e7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.obj/
+compile_commands.json
+.ninja_log
+
diff --git a/build/ab.py b/build/ab.py
index 81e3c9fff..56dc4c892 100644
--- a/build/ab.py
+++ b/build/ab.py
@@ -526,6 +526,7 @@ def generate(xs):
 
 
 def filenameof(x):
+    x = targetof(x)
     xs = filenamesof(x.outs)
     assert (
         len(xs) == 1
@@ -611,7 +612,7 @@ def emit_rule(self, ins, outs, cmds=[], label=None):
             emit("build", *fouts, ":rule", *fins)
             emit(
                 " command=",
-                "&&".join([s.strip() for s in rule]).replace("$", "$$"),
+                " && ".join([s.strip() for s in rule]).replace("$", "$$"),
             )
         if label:
             emit(" description=", label)
diff --git a/plat/cpm/emu/build.py b/plat/cpm/emu/build.py
index 426b31fbd..63e4e5690 100644
--- a/plat/cpm/emu/build.py
+++ b/plat/cpm/emu/build.py
@@ -21,7 +21,7 @@
         "util/amisc+aslod",
         ".+bdos_out",
     ],
-    outs=["bdos.img"],
+    outs=["=bdos.img"],
     commands=["$[ins] $[outs]"],
 )