diff --git a/rlimit_windows.go b/rlimit_nonposix.go
similarity index 85%
rename from rlimit_windows.go
rename to rlimit_nonposix.go
index 0288102f5..198c9d9f8 100644
--- a/rlimit_windows.go
+++ b/rlimit_nonposix.go
@@ -1,3 +1,5 @@
+// +build windows plan9
+
 package caddy
 
 // checkFdlimit issues a warning if the OS limit for
diff --git a/rlimit_posix.go b/rlimit_posix.go
index e63987767..a270e1f2b 100644
--- a/rlimit_posix.go
+++ b/rlimit_posix.go
@@ -1,4 +1,4 @@
-// +build !windows
+// +build !windows,!plan9
 
 package caddy
 
diff --git a/sigtrap_windows.go b/sigtrap_nonposix.go
similarity index 62%
rename from sigtrap_windows.go
rename to sigtrap_nonposix.go
index cbe7c0199..0b2e6d3ed 100644
--- a/sigtrap_windows.go
+++ b/sigtrap_nonposix.go
@@ -1,3 +1,5 @@
+// +build windows plan9
+
 package caddy
 
 func trapSignalsPosix() {}
diff --git a/sigtrap_posix.go b/sigtrap_posix.go
index 54cbebcb7..b4cbd9c6f 100644
--- a/sigtrap_posix.go
+++ b/sigtrap_posix.go
@@ -1,4 +1,4 @@
-// +build !windows
+// +build !windows,!plan9
 
 package caddy