diff --git a/pkgs/build-support/testers/testBuildFailurePrime/build-command.sh b/pkgs/build-support/testers/testBuildFailurePrime/build-command.sh
index f3f292a5f724..f4747ff3f76c 100644
--- a/pkgs/build-support/testers/testBuildFailurePrime/build-command.sh
+++ b/pkgs/build-support/testers/testBuildFailurePrime/build-command.sh
@@ -2,34 +2,40 @@
 
 set -eu
 
-scriptPhase() {
-  runHook preScript
+declare -ag preScriptHooks=(testBuilderExitCode)
+# shellcheck disable=SC2154
+((${#expectedBuilderLogEntries[@]})) && preScriptHooks+=(testBuilderLogEntries)
 
+testBuilderExitCode() {
   nixLog "checking original builder exit code"
   local -ir builderExitCode=$(<"${failed:?}/testBuildFailure.exit")
   # shellcheck disable=SC2154
   if ((expectedBuilderExitCode == builderExitCode)); then
     nixLog "original builder exit code matches expected value of $expectedBuilderExitCode"
+    return 0
   else
     nixErrorLog "original builder produced exit code $builderExitCode but was expected to produce $expectedBuilderExitCode"
-    exit 1
+    return 1
   fi
+}
 
-  # shellcheck disable=SC2154
-  if ((${#expectedBuilderLogEntries[@]})); then
-    nixLog "checking original builder log"
-    local -r builderLogEntries="$(<"${failed:?}/testBuildFailure.log")"
-    local -i shouldExit=0
-    for expectedBuilderLogEntry in "${expectedBuilderLogEntries[@]}"; do
-      if [[ ${builderLogEntries} == *"$expectedBuilderLogEntry"* ]]; then
-        nixLog "original builder log contains ${expectedBuilderLogEntry@Q}"
-      else
-        nixErrorLog "original builder log does not contain ${expectedBuilderLogEntry@Q}"
-        shouldExit=1
-      fi
-    done
-    ((shouldExit)) && exit 1
-  fi
+testBuilderLogEntries() {
+  nixLog "checking original builder log"
+  local -r builderLogEntries="$(<"${failed:?}/testBuildFailure.log")"
+  local -i shouldExit=0
+  for expectedBuilderLogEntry in "${expectedBuilderLogEntries[@]}"; do
+    if [[ ${builderLogEntries} == *"$expectedBuilderLogEntry"* ]]; then
+      nixLog "original builder log contains ${expectedBuilderLogEntry@Q}"
+    else
+      nixErrorLog "original builder log does not contain ${expectedBuilderLogEntry@Q}"
+      shouldExit=1
+    fi
+  done
+  return $shouldExit
+}
+
+scriptPhase() {
+  runHook preScript
 
   runHook script