diff --git a/source/src/commands/validate-template.cpp b/source/src/commands/validate-template.cpp
index 29fb58d..c583e74 100644
--- a/source/src/commands/validate-template.cpp
+++ b/source/src/commands/validate-template.cpp
@@ -86,12 +86,13 @@ int run_shellcheck(const std::filesystem::path& template_path, std::vector<std::
         // Get relative path from template_path
         std::string rel_path = std::filesystem::relative(script, template_path).string();
 
-        // Run shellcheck in container
+        // Run shellcheck in container, piping script via stdin to avoid
+        // volume mount issues in Docker-in-Docker CI environments
         // -f gcc gives us parseable output: file:line:col: severity: message
         // -s bash specifies bash dialect
         // -e SC1091 excludes "not following sourced file" warnings (common.sh is external)
-        std::string command = "docker run --rm -v " + template_path.string() + ":/mnt:ro koalaman/shellcheck:stable "
-                              "-f gcc -s bash -e SC1091 /mnt/" + rel_path + " 2>&1";
+        std::string command = "cat " + script.string() + " | docker run --rm -i koalaman/shellcheck:stable "
+                              "-f gcc -s bash -e SC1091 - 2>&1";
 
         FILE* pipe = popen(command.c_str(), "r");
         if (!pipe) {
@@ -118,10 +119,14 @@ int run_shellcheck(const std::filesystem::path& template_path, std::vector<std::
             while (std::getline(iss, line)) {
                 if (line.empty()) continue;
 
-                // Replace /mnt/ with actual filename for clarity
-                size_t mnt_pos = line.find("/mnt/");
-                if (mnt_pos != std::string::npos) {
-                    line = line.substr(mnt_pos + 5); // Skip "/mnt/"
+                // Replace stdin placeholder or /mnt/ path with actual filename
+                if (line.substr(0, 2) == "-:") {
+                    line = rel_path + ":" + line.substr(2);
+                } else {
+                    size_t mnt_pos = line.find("/mnt/");
+                    if (mnt_pos != std::string::npos) {
+                        line = line.substr(mnt_pos + 5); // Skip "/mnt/"
+                    }
                 }
 
                 // Color based on severity