diff --git a/build.nims b/build.nims
index 23e3eeca7..3d1a3cac4 100644
--- a/build.nims
+++ b/build.nims
@@ -1,5 +1,6 @@
 mode = ScriptMode.Verbose
 
+import std/os except commandLineParams
 
 ### Helper functions
 proc buildBinary(name: string, srcDir = "./", params = "", lang = "c") =
@@ -14,7 +15,11 @@ proc buildBinary(name: string, srcDir = "./", params = "", lang = "c") =
     for i in 2..<paramCount():
       extra_params &= " " & paramStr(i)
 
-  let cmd = "nim " & lang & " --out:build/" & name & " " & extra_params & " " & srcDir & name & ".nim"
+  let
+    # Place build output in 'build' folder, even if name includes a longer path.
+    outName = os.lastPathPart(name)
+    cmd = "nim " & lang & " --out:build/" & outName & " " & extra_params & " " & srcDir & name & ".nim"
+
   exec(cmd)
 
 proc test(name: string, srcDir = "tests/", params = "", lang = "c") =
@@ -25,7 +30,7 @@ task codex, "build codex binary":
   buildBinary "codex", params = "-d:chronicles_runtime_filtering -d:chronicles_log_level=TRACE"
 
 task toolsCirdl, "build tools/cirdl binary":
-  buildBinary "tools/cirdl/cirdl", params = ""
+  buildBinary "tools/cirdl/cirdl"
 
 task testCodex, "Build & run Codex tests":
   test "testCodex", params = "-d:codex_enable_proof_failures=true"