Index: Makefile
===================================================================
--- Makefile
+++ Makefile
@@ -352,7 +352,12 @@
 	@false
 
 STARTTIME!= LC_ALL=C date
-CHECK_TIME!= find ${.CURDIR}/sys/sys/param.h -mtime -0s ; echo
+.if ${.MAKE.OS} != "Linux
+# One Linux /usr/bin/find only supports integer literals in the mtime flag
+# This does the same so we can skip it when building on Linux
+MTIME_SECONDS_SUFFIX=s
+.endif
+CHECK_TIME!= find ${.CURDIR}/sys/sys/param.h -mtime -0${MTIME_SECONDS_SUFFIX} ; echo
 .if !empty(CHECK_TIME)
 .error check your date/time: ${STARTTIME}
 .endif