diff --git a/R/gs_design_ahr.R b/R/gs_design_ahr.R
index 071df325..75095726 100644
--- a/R/gs_design_ahr.R
+++ b/R/gs_design_ahr.R
@@ -236,6 +236,9 @@ gs_design_ahr <- function(
   if ((length(analysis_time) > 1) && (length(info_frac) > 1) && (length(info_frac) != length(analysis_time))) {
     stop("gs_design_ahr() info_frac and analysis_time must have the same length if both have length > 1.")
   }
+  if(all(fail_rate$hr == 1)){
+    stop("gs_design_ahr() hr must not be equal to 1 throughout the study as this is the null hypothesis.")
+  }
 
   # --------------------------------------------- #
   #     check if alpha is same as alpha spending  #
diff --git a/R/gs_design_combo.R b/R/gs_design_combo.R
index f86e7260..0d831986 100644
--- a/R/gs_design_combo.R
+++ b/R/gs_design_combo.R
@@ -178,6 +178,10 @@ gs_design_combo <- function(
     two_sided <- TRUE
   }
 
+  if(all(fail_rate$hr == 1)){
+    stop("gs_design_combo() hr must not be equal to 1 throughout the study as this is the null hypothesis.")
+  }
+
   # Information Fraction
   if (n_analysis == 1) {
     min_info_frac <- 1
diff --git a/R/gs_design_wlr.R b/R/gs_design_wlr.R
index 48d74245..916b3b30 100644
--- a/R/gs_design_wlr.R
+++ b/R/gs_design_wlr.R
@@ -152,6 +152,9 @@ gs_design_wlr <- function(
   if (max(info_frac) != 1) stop(msg)
   msg <- "gs_design_wlr(): info_frac and analysis_time must have the same length if both have length > 1"
   if ((length(analysis_time) > 1) && (length(info_frac) > 1) && (length(info_frac) != length(analysis_time))) stop(msg)
+  if(all(fail_rate$hr == 1)){
+    stop("gs_design_wlr() hr must not be equal to 1 throughout the study as this is the null hypothesis.")
+  }
   # get the info_scale
   info_scale <- match.arg(info_scale)