diff --git a/zig-c-interop/Makefile b/zig-c-interop/Makefile
index b0e2753d5367fcfa90c7d7e0ce69c9cf2e2b5739..5d19def8bea58b43d39c48921c3a53da52179cea 100644
--- a/zig-c-interop/Makefile
+++ b/zig-c-interop/Makefile
@@ -1,2 +1,4 @@
+# It is important to add Include path of local directory with "-I." so
+# that Zig compiler knows where to find C files.
 default:
 	zig run -I. main.zig