diff --git a/build.zsh.in b/build.zsh.in
index 207ba50..6d144d0 100644
--- a/build.zsh.in
+++ b/build.zsh.in
@@ -174,10 +174,20 @@ function duplicated {
 
 function dirdep {
 	dirname="$(dirname "$1")"
+	local sources=(${(@s/ /)2})
+	local depends=(${(@s/ /)3})
 
-	if [[ "$dirname" != "." ]]; then
-		echo "$dirname"
+	for dep in ${sources[@]} ${depends[@]}; do
+		if [[ "$(dirname $dep)" == "$dirname" ]]; then
+			return 0
+		fi
+	done
+
+	if [[ "$dirname" == "." ]]; then
+		return 0
 	fi
+
+	echo "$dirname"
 }
 
 for dir in "@SHAREDIR@/build.zsh" ./build; do
diff --git a/build/ofile.zsh b/build/ofile.zsh
index 9f02334..1136e69 100644
--- a/build/ofile.zsh
+++ b/build/ofile.zsh
@@ -1,7 +1,7 @@
 
 function ofile.build {
 	local dirname="$(dirname "$target")"
-	write -n "${target}: ${target%.o}.c $(dirdep $target)"
+	write -n "${target}: ${target%.o}.c $(dirdep $target "${target%.o}.c ${sources[$target]}" "${depends[@target]}")"
 
 	sed '/^#include "/!d;s/^#include "//;s/"$//' "${target%.o}.c" | \
 	while read h; do