diff --git a/DESCRIPTION b/DESCRIPTION
index f31d3e1a..c90753c5 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -10,7 +10,7 @@ Description: Automates fixed item parameter linking for test linking under
     the item response theory paradigm using mirt package estimates.
 License: GPL-3 | file LICENSE
 Imports: mirt, methods
-Suggests: testthat (>= 3.0.0)
+Suggests: testthat (>= 3.0.0), mockery
 Encoding: UTF-8
 Config/testthat/edition: 3
 Config/roxygen2/version: 8.0.0
diff --git a/R/aFIPC.R b/R/aFIPC.R
index 62546519..918e19b1 100644
--- a/R/aFIPC.R
+++ b/R/aFIPC.R
@@ -141,7 +141,7 @@ autoFIPC <-
       }
       for (attempt in seq_len(3)) {
         n <- readline(prompt = "Is it correct? (1: Yes 2: No) : ")
-        if (grepl("^[0-9]+$", n)) {
+        if (grepl("^[12]$", n)) {
           return(as.integer(n))
         }
       }
@@ -171,7 +171,7 @@ autoFIPC <-
               readline(
                 prompt = "Do you want to use default BILOG-MG priors for oldform Data? (1: Yes 2: No) : "
               )
-            if (grepl("^[0-9]+$", n)) {
+            if (grepl("^[12]$", n)) {
               return(as.integer(n))
             }
           }
@@ -390,7 +390,7 @@ autoFIPC <-
               readline(
                 prompt = "Do you want to use default BILOG-MG priors for newform Data? (1: Yes 2: No) : "
               )
-            if (grepl("^[0-9]+$", n)) {
+            if (grepl("^[12]$", n)) {
               return(as.integer(n))
             }
           }
diff --git a/tests/testthat/test-sentinel-integer-coercion.R b/tests/testthat/test-sentinel-integer-coercion.R
new file mode 100644
index 00000000..adb87e2e
--- /dev/null
+++ b/tests/testthat/test-sentinel-integer-coercion.R
@@ -0,0 +1,73 @@
+test_that("interactive readline valid inputs", {
+  # For valid inputs, it should correctly parse the '1' and eventually hit the estimation
+  # We test the prompt reading by providing minimal data that causes mirt to fail early
+  # but after the prompt logic.
+
+  mock_readline_confirm <- mockery::mock('1')
+  mockery::stub(aFIPC::autoFIPC, 'interactive', TRUE)
+  mockery::stub(aFIPC::autoFIPC, 'readline', mock_readline_confirm)
+
+  # A 100x4 matrix works better to avoid degrees of freedom errors in some cases,
+  # but our goal is just to pass the `checkCorrect()` prompt logic.
+  expect_error(
+    aFIPC::autoFIPC(
+      newformXData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      oldformYData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      newformCommonItemNames = 'I1',
+      oldformCommonItemNames = 'I1',
+      itemtype = '3PL',
+      newformBILOGprior = TRUE,
+      oldformBILOGprior = TRUE,
+      confirmCommonItems = NULL
+    )
+  )
+})
+
+test_that("interactive readline invalid inputs", {
+  # Mock invalid inputs
+  mock_readline_invalid <- mockery::mock('3', 'a', '9999999999999999999999999999999', cycle = TRUE)
+  mockery::stub(aFIPC::autoFIPC, 'interactive', TRUE)
+  mockery::stub(aFIPC::autoFIPC, 'readline', mock_readline_invalid)
+
+  expect_error(
+    aFIPC::autoFIPC(
+      newformXData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      oldformYData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      newformCommonItemNames = 'I1',
+      oldformCommonItemNames = 'I1',
+      itemtype = '3PL',
+      newformBILOGprior = NULL,
+      oldformBILOGprior = TRUE,
+      confirmCommonItems = TRUE
+    ),
+    "Too many invalid newform BILOG prior attempts"
+  )
+
+  expect_error(
+    aFIPC::autoFIPC(
+      newformXData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      oldformYData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      newformCommonItemNames = 'I1',
+      oldformCommonItemNames = 'I1',
+      itemtype = '3PL',
+      newformBILOGprior = TRUE,
+      oldformBILOGprior = NULL,
+      confirmCommonItems = TRUE
+    ),
+    "Too many invalid oldform BILOG prior attempts"
+  )
+
+  expect_error(
+    aFIPC::autoFIPC(
+      newformXData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      oldformYData = matrix(sample(c(0,1), 1000, replace=T), ncol=10, dimnames=list(NULL, paste0('I',1:10))),
+      newformCommonItemNames = 'I1',
+      oldformCommonItemNames = 'I1',
+      itemtype = '3PL',
+      newformBILOGprior = TRUE,
+      oldformBILOGprior = TRUE,
+      confirmCommonItems = NULL
+    ),
+    "Too many invalid common item confirmation attempts"
+  )
+})