diff --git a/Mk/Uses/firebird.mk b/Mk/Uses/firebird.mk
index 23aaf9c5eb65..63123bf5f503 100644
--- a/Mk/Uses/firebird.mk
+++ b/Mk/Uses/firebird.mk
@@ -1,33 +1,27 @@
 # Provide support for Firebird
 # Feature:	firebird
 # Usage:	USES=	firebird[:version]
 # MAINTAINER:	ports@FreeBSD.org
 
 .if !defined(_INCLUDE_USES_FIREBIRD_MK)
 _INCLUDE_USES_FIREBIRD_MK=	yes
 
 .  if !empty(firebird_ARGS)
 FIREBIRD_VER=	${firebird_ARGS}
 .  else
 FIREBIRD_VER=	${FIREBIRD_DEFAULT}
 .  endif
 
 # When adding a version, please keep the comment in
 # Mk/bsd.default-versions.mk in sync.
 VALID_FIREBIRD_VER=        2.5 3.0 4.0
 
-.  for v in ${FIREBIRD_DEFAULT}
-.    if ! ${VALID_FIREBIRD_VER:M$v}
+.  if ! ${VALID_FIREBIRD_VER:M${FIREBIRD_DEFAULT}}
 IGNORE=		Invalid Firebird default version ${FIREBIRD_DEFAULT}; valid versions are ${VALID_FIREBIRD_VER}
-.    endif
-.  endfor
-
-.  for w in ${FIREBIRD_VER}
-.    if ! ${VALID_FIREBIRD_VER:M$w}
+.  elif ! ${VALID_FIREBIRD_VER:M${FIREBIRD_VER}}
 IGNORE=		Invalid Firebird version ${FIREBIRD_VER}; valid versions are ${VALID_FIREBIRD_VER}
-.    endif
-.  endfor
+.  endif
 
 LIB_DEPENDS+=	libfbclient.so:databases/firebird${FIREBIRD_VER:S/.//}-client
 
 .endif