diff --git a/Irpg/Classes/Farmer.pm b/Irpg/Classes/Farmer.pm
index 06c395b3a76de1e0a5c332d8322f20449a84f95c..7512195f34f8e32f8b6ec9994e0dd0127207b73a 100644
--- a/Irpg/Classes/Farmer.pm
+++ b/Irpg/Classes/Farmer.pm
@@ -83,6 +83,7 @@ sub real_gain {
 	# to apply on TTL modificators
 	my ($self, $time) = @_;
 	return unless ($time =~ m/^-?\d+$/);
+	return unless ($time =~ m/^-?\d+(?:\.\d+$)?/);
 	$time = $time >= 0 ?
 		$time*(1-($self->cha()-1)/20):	# add less time
 		$time*(1+($self->cha()-1)/20);	# remove more time