diff --git a/difftest/run-emulator.nix b/difftest/run-emulator.nix
index baee3ec7a2..0c8924c2db 100644
--- a/difftest/run-emulator.nix
+++ b/difftest/run-emulator.nix
@@ -2,6 +2,9 @@
 emulator:
 testCase:
 
+let
+  impureEnvs = import (../../nix/impure.nix);
+in
 runCommand "run-${emulator.name}-for-${testCase.pname}"
 {
   name = "${testCase.pname}-emu-result" + (lib.optionalString emulator.enable-trace "-trace");
@@ -50,10 +53,19 @@ runCommand "run-${emulator.name}-for-${testCase.pname}"
   fi
 
   set +e
-  "${emulator}/bin/offline" \
-    --elf-file ${testCase}/bin/${testCase.pname}.elf \
-    --log-file $rtlEventOutPath \
-    --log-level ERROR &> $out/offline-check-journal
+  offlineCheckArgsArray=(
+    "--elf-file"
+    "${testCase}/bin/${testCase.pname}.elf"
+    "--log-file"
+    "$rtlEventOutPath"
+    "--log-level"
+    "${impureEnvs.t1OfflineLogLevel}"
+  )
+  offlineCheckArgs="''${offlineCheckArgsArray[@]}"
+
+  echo "[nix] running ${emulator}/bin/offline $offlineCheckArgs"
+  "${emulator}/bin/offline" $offlineCheckArgs &> $out/offline-check-journal
+
   printf "$?" > $out/offline-check-status
   if [ "$(cat $out/offline-check-status)" != "0" ]; then
     echo "[nix] Offline check FAIL"
diff --git a/nix/impure.nix b/nix/impure.nix
new file mode 100644
index 0000000000..019528e1a6
--- /dev/null
+++ b/nix/impure.nix
@@ -0,0 +1,4 @@
+rec {
+  t1OfflineLogLevelEnv = builtins.getEnv "T1_OFFLINE_LOG_LEVEL";
+  t1OfflineLogLevel = if t1OfflineLogLevelEnv != "" then t1OfflineLogLevelEnv else "ERROR";
+}
diff --git a/nix/t1/run-vcs-emulation.nix b/nix/t1/run-vcs-emulation.nix
index 8c4f9f3c7e..78307194f4 100644
--- a/nix/t1/run-vcs-emulation.nix
+++ b/nix/t1/run-vcs-emulation.nix
@@ -3,6 +3,9 @@
 emulator:
 testCase:
 
+let
+  impureEnvs = import (../../nix/impure.nix);
+in
 runCommand "run-${emulator.name}-for-${testCase.pname}"
 {
   name = "${testCase.pname}-vcs-result" + (lib.optionalString emulator.enable-trace "-trace");
@@ -48,10 +51,19 @@ runCommand "run-${emulator.name}-for-${testCase.pname}"
   fi
 
   set +e
-  "${verilator-emu}/bin/offline" \
-    --elf-file ${testCase}/bin/${testCase.pname}.elf \
-    --log-file $rtlEventOutPath \
-    --log-level ERROR &> $out/offline-check-journal
+  offlineCheckArgsArray=(
+    "--elf-file"
+    "${testCase}/bin/${testCase.pname}.elf"
+    "--log-file"
+    "$rtlEventOutPath"
+    "--log-level"
+    "${impureEnvs.t1OfflineLogLevel}"
+  )
+  offlineCheckArgs="''${offlineCheckArgsArray[@]}"
+
+  echo "[nix] running ${emulator}/bin/offline $offlineCheckArgs"
+  "${emulator}/bin/offline" $offlineCheckArgs &> $out/offline-check-journal
+
   printf "$?" > $out/offline-check-status
   if [ "$(cat $out/offline-check-status)" != "0" ]; then
     echo "[nix] Offline check FAIL"
diff --git a/t1rocketemu/nix/run-emulator.nix b/t1rocketemu/nix/run-emulator.nix
index cd2fdfc3ac..ce0ce73fee 100644
--- a/t1rocketemu/nix/run-emulator.nix
+++ b/t1rocketemu/nix/run-emulator.nix
@@ -2,6 +2,9 @@
 emulator:
 testCase:
 
+let
+  impureEnvs = import (../../nix/impure.nix);
+in
 runCommand ("${emulator.name}-${testCase.pname}-emu-result" + lib.optionalString emulator.enable-trace "-trace")
 {
   nativeBuildInputs = [ zstd jq ];
@@ -49,10 +52,19 @@ runCommand ("${emulator.name}-${testCase.pname}-emu-result" + lib.optionalString
   fi
 
   set +e
-  "${emulator}/bin/offline" \
-    --elf-file ${testCase}/bin/${testCase.pname}.elf \
-    --log-file $rtlEventOutPath \
-    --log-level ERROR &> $out/offline-check-journal
+  offlineCheckArgsArray=(
+    "--elf-file"
+    "${testCase}/bin/${testCase.pname}.elf"
+    "--log-file"
+    "$rtlEventOutPath"
+    "--log-level"
+    "${impureEnvs.t1OfflineLogLevel}"
+  )
+  offlineCheckArgs="''${offlineCheckArgsArray[@]}"
+
+  echo "[nix] running ${emulator}/bin/offline $offlineCheckArgs"
+  "${emulator}/bin/offline" $offlineCheckArgs &> $out/offline-check-journal
+
   printf "$?" > $out/offline-check-status
   if [ "$(cat $out/offline-check-status)" != "0" ]; then
     echo "[nix] Offline check FAIL"
diff --git a/t1rocketemu/nix/run-vcs-emulation.nix b/t1rocketemu/nix/run-vcs-emulation.nix
index d4df55cb08..7b7f2a106b 100644
--- a/t1rocketemu/nix/run-vcs-emulation.nix
+++ b/t1rocketemu/nix/run-vcs-emulation.nix
@@ -3,6 +3,9 @@
 emulator:
 testCase:
 
+let
+  impureEnvs = import (../../nix/impure.nix);
+in
 runCommand "run-${emulator.name}-for-${testCase.pname}"
 {
   name = "${testCase.pname}-vcs-result" + (lib.optionalString emulator.enable-trace "-trace");
@@ -48,10 +51,18 @@ runCommand "run-${emulator.name}-for-${testCase.pname}"
   fi
 
   set +e
-  "${verilator-emu}/bin/offline" \
-    --elf-file ${testCase}/bin/${testCase.pname}.elf \
-    --log-file $rtlEventOutPath \
-    --log-level ERROR &> $out/offline-check-journal
+  offlineCheckArgsArray=(
+    "--elf-file"
+    "${testCase}/bin/${testCase.pname}.elf"
+    "--log-file"
+    "$rtlEventOutPath"
+    "--log-level"
+    "${impureEnvs.t1OfflineLogLevel}"
+  )
+  offlineCheckArgs="''${offlineCheckArgsArray[@]}"
+
+  echo "[nix] running ${emulator}/bin/offline $offlineCheckArgs"
+  "${emulator}/bin/offline" $offlineCheckArgs &> $out/offline-check-journal
   printf "$?" > $out/offline-check-status
   if [ "$(cat $out/offline-check-status)" != "0" ]; then
     echo "[nix] Offline check FAIL"