diff --git a/R/getters.R b/R/getters.R
index 2a3f52b..8510a88 100644
--- a/R/getters.R
+++ b/R/getters.R
@@ -101,7 +101,7 @@ get_3_n_params <- function(fractional = TRUE,
 
     data.frame(
       start = c(n_1 = MaxUptake/3, n_2 = MaxUptake/3, n_3 = MaxUptake/3),
-      lower = c(n_1 = 0, n_2 = 0, n_3 = 0),
+      lower = c(n_1 = 1, n_2 = 1, n_3 = 1),
       upper = c(n_1 = MaxUptake, n_2 = MaxUptake, n_3 = MaxUptake)
     )
 
@@ -135,7 +135,7 @@ get_2_n_params <- function(fractional = TRUE,
 
     data.frame(
       start = c(n_1 = MaxUptake/2, n_2 = MaxUptake/2),
-      lower = c(n_1 = 0, n_2 = 0),
+      lower = c(n_1 = 1, n_2 = 1),
       upper = c(n_1 = MaxUptake, n_2 = MaxUptake)
     )
   }
@@ -168,7 +168,7 @@ get_1_n_params <- function(fractional = TRUE,
 
     data.frame(
       start = c(n_1 = MaxUptake*0.7),
-      lower = c(n_1 = 0),
+      lower = c(n_1 = 1),
       upper = c(n_1 = MaxUptake)
     )