diff --git a/R/extract_param.R b/R/extract_param.R
index 55a37727f..16f9857af 100644
--- a/R/extract_param.R
+++ b/R/extract_param.R
@@ -214,18 +214,22 @@ extract_param <- function(type = c("percentiles", "range"),
   if (distribution == "lnorm") {
     names(param) <- c("meanlog", "sdlog")
     lower <- c(-1e5, 1e-10)
+    upper <- c(1e10, 1e10)
   }
   if (distribution == "gamma") {
     names(param) <- c("shape", "scale")
     lower <- c(1e-10, 1e-10)
+    upper <- c(1e10, 1e10)
   }
   if (distribution == "weibull") {
     names(param) <- c("shape", "scale")
     lower <- c(1e-10, 1e-10)
+    upper <- c(1e10, 1e10)
   }
   if (distribution == "norm") {
     names(param) <- c("mean", "sd")
     lower <- c(-1e5, 1e-10)
+    upper <- c(1e10, 1e10)
   }
 
   optim_params <- tryCatch(stats::optim(