diff --git a/yasm_assemble.gni b/yasm_assemble.gni
index b05bcf5..1724f01 100644
--- a/yasm_assemble.gni
+++ b/yasm_assemble.gni
@@ -91,17 +91,19 @@
     script = "//third_party/yasm/run_yasm.py"
     sources = invoker.sources
 
-    if (defined(invoker.inputs)) {
-      inputs = invoker.inputs
-    }
-
     # Executable (first in the args). The binary might be in the root build dir
     # (no cross-compiling) or in a toolchain-specific subdirectory of that
     # (when cross-compiling).
     yasm_label = "//third_party/yasm($host_toolchain)"
+    yasm_path = get_label_info(yasm_label, "root_out_dir") + "/yasm"
     args = [ "./" +  # Force current dir.
-             rebase_path(get_label_info(yasm_label, "root_out_dir") + "/yasm",
-                         root_build_dir) ]
+             rebase_path(yasm_path, root_build_dir) ]
+
+    # List the yasm binary as an input so the action is re-run when it changes.
+    inputs = [ yasm_path ]
+    if (defined(invoker.inputs)) {
+      inputs += invoker.inputs
+    }
 
     # Deps.
     deps = [