diff --git a/tf/toolchains/terraform/toolchain.bzl b/tf/toolchains/terraform/toolchain.bzl
index 21c8e9f..eac48f9 100644
--- a/tf/toolchains/terraform/toolchain.bzl
+++ b/tf/toolchains/terraform/toolchain.bzl
@@ -72,12 +72,16 @@ def _download_impl(ctx):
 
     ctx.file("versions.tf.json", content = json.encode(versions_tf))
 
-    ctx.execute([
+    result = ctx.execute([
         "bash",
         "-c",
-        "mkdir -p mirror; terraform/terraform providers mirror ./mirror > /dev/null",
+        "mkdir -p mirror; terraform/terraform providers mirror ./mirror",
         ])
 
+    if result.return_code != 0:
+        fail("terraform providers mirror failed (exit {}):\n{}\n{}".format(
+            result.return_code, result.stdout, result.stderr))
+
     return
 
 terraform_download = repository_rule(
diff --git a/tf/toolchains/tofu/toolchain.bzl b/tf/toolchains/tofu/toolchain.bzl
index e68ab62..3ed2895 100644
--- a/tf/toolchains/tofu/toolchain.bzl
+++ b/tf/toolchains/tofu/toolchain.bzl
@@ -72,12 +72,16 @@ def _download_impl(ctx):
 
     ctx.file("versions.tf.json", content = json.encode(versions_tf))
 
-    ctx.execute([
+    result = ctx.execute([
         "bash",
         "-c",
-        "mkdir -p mirror; tofu/tofu providers mirror ./mirror > /dev/null",
+        "mkdir -p mirror; tofu/tofu providers mirror ./mirror",
         ])
 
+    if result.return_code != 0:
+        fail("tofu providers mirror failed (exit {}):\n{}\n{}".format(
+            result.return_code, result.stdout, result.stderr))
+
     return
 
 tofu_download = repository_rule(