diff --git a/src/cache.cpp b/src/cache.cpp
index 6042608..e4a140b 100644
--- a/src/cache.cpp
+++ b/src/cache.cpp
@@ -346,18 +346,14 @@ bool StatCache::AddStat(const std::string& key, const headers_t& meta, bool forc
     SetStatCacheTime(ent.cache_date);    // Set time.
     //copy only some keys
     for(auto iter = meta.cbegin(); iter != meta.cend(); ++iter){
-        std::string tag   = lower(iter->first);
+        auto tag          = CaseInsensitiveStringView(iter->first);
         const auto& value = iter->second;
-        if(tag == "content-type"){
+        if(tag == "content-type" ||
+           tag == "content-length" ||
+           tag == "etag" ||
+           tag == "last-modified" ||
+           tag.is_prefix("x-amz")){
             ent.meta[iter->first] = value;
-        }else if(tag == "content-length"){
-            ent.meta[iter->first] = value;
-        }else if(tag == "etag"){
-            ent.meta[iter->first] = value;
-        }else if(tag == "last-modified"){
-            ent.meta[iter->first] = value;
-        }else if(is_prefix(tag.c_str(), "x-amz")){
-            ent.meta[tag] = value;      // key is lower case for "x-amz"
         }
     }
 
@@ -403,18 +399,14 @@ bool StatCache::UpdateMetaStats(const std::string& key, const headers_t& meta)
 
     // update only meta keys
     for(auto metaiter = meta.cbegin(); metaiter != meta.cend(); ++metaiter){
-        std::string tag   = lower(metaiter->first);
+        auto tag          = CaseInsensitiveStringView(metaiter->first);
         const auto& value = metaiter->second;
-        if(tag == "content-type"){
+        if(tag == "content-type" ||
+           tag == "content-length" ||
+           tag == "etag" ||
+           tag == "last-modified" ||
+           tag.is_prefix("x-amz")){
             ent->meta[metaiter->first] = value;
-        }else if(tag == "content-length"){
-            ent->meta[metaiter->first] = value;
-        }else if(tag == "etag"){
-            ent->meta[metaiter->first] = value;
-        }else if(tag == "last-modified"){
-            ent->meta[metaiter->first] = value;
-        }else if(is_prefix(tag.c_str(), "x-amz")){
-            ent->meta[tag] = value;      // key is lower case for "x-amz"
         }
     }
 
diff --git a/src/curl.cpp b/src/curl.cpp
index 230f2c6..ac02857 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -3416,18 +3416,14 @@ int S3fsCurl::HeadRequest(const char* tpath, headers_t& meta)
     // fixme: clean this up.
     meta.clear();
     for(auto iter = responseHeaders.cbegin(); iter != responseHeaders.cend(); ++iter){
-        std::string key   = lower(iter->first);
+        auto key          = CaseInsensitiveStringView(iter->first);
         const auto& value = iter->second;
-        if(key == "content-type"){
+        if(key == "content-type" ||
+           key == "content-length" ||
+           key == "etag" ||
+           key == "last-modified" ||
+           key.is_prefix("x-amz")){
             meta[iter->first] = value;
-        }else if(key == "content-length"){
-            meta[iter->first] = value;
-        }else if(key == "etag"){
-            meta[iter->first] = value;
-        }else if(key == "last-modified"){
-            meta[iter->first] = value;
-        }else if(is_prefix(key.c_str(), "x-amz")){
-            meta[key] = value;        // key is lower case for "x-amz"
         }
     }
     return 0;
@@ -3458,11 +3454,11 @@ int S3fsCurl::PutHeadRequest(const char* tpath, headers_t& meta, bool is_copy)
 
     // Make request headers
     for(auto iter = meta.cbegin(); iter != meta.cend(); ++iter){
-        std::string key   = lower(iter->first);
+        auto key          = CaseInsensitiveStringView(iter->first);
         const auto& value = iter->second;
-        if(is_prefix(key.c_str(), "x-amz-acl")){
+        if(key.is_prefix("x-amz-acl")){
             // not set value, but after set it.
-        }else if(is_prefix(key.c_str(), "x-amz-meta")){
+        }else if(key.is_prefix("x-amz-meta")){
             requestHeaders = curl_slist_sort_insert(requestHeaders, iter->first.c_str(), value.c_str());
         }else if(key == "x-amz-copy-source"){
             requestHeaders = curl_slist_sort_insert(requestHeaders, iter->first.c_str(), value.c_str());
@@ -3595,11 +3591,11 @@ int S3fsCurl::PutRequest(const char* tpath, headers_t& meta, int fd)
     requestHeaders = curl_slist_sort_insert(requestHeaders, "Content-Type", contype.c_str());
 
     for(auto iter = meta.cbegin(); iter != meta.cend(); ++iter){
-        std::string key   = lower(iter->first);
+        auto key          = CaseInsensitiveStringView(iter->first);
         const auto& value = iter->second;
-        if(is_prefix(key.c_str(), "x-amz-acl")){
+        if(key.is_prefix("x-amz-acl")){
             // not set value, but after set it.
-        }else if(is_prefix(key.c_str(), "x-amz-meta")){
+        }else if(key.is_prefix("x-amz-meta")){
             requestHeaders = curl_slist_sort_insert(requestHeaders, iter->first.c_str(), value.c_str());
         }else if(key == "x-amz-server-side-encryption" && value != "aws:kms"){
             // skip this header, because this header is specified after logic.
@@ -3920,11 +3916,11 @@ int S3fsCurl::PreMultipartPostRequest(const char* tpath, headers_t& meta, std::s
     std::string contype = S3fsCurl::LookupMimeType(tpath);
 
     for(auto iter = meta.cbegin(); iter != meta.cend(); ++iter){
-        std::string key   = lower(iter->first);
+        auto key          = CaseInsensitiveStringView(iter->first);
         const auto& value = iter->second;
-        if(is_prefix(key.c_str(), "x-amz-acl")){
+        if(key.is_prefix("x-amz-acl")){
             // not set value, but after set it.
-        }else if(is_prefix(key.c_str(), "x-amz-meta")){
+        }else if(key.is_prefix("x-amz-meta")){
             requestHeaders = curl_slist_sort_insert(requestHeaders, iter->first.c_str(), value.c_str());
         }else if(key == "x-amz-server-side-encryption" && value != "aws:kms"){
             // skip this header, because this header is specified after logic.
@@ -4326,7 +4322,7 @@ int S3fsCurl::CopyMultipartPostSetup(const char* from, const char* to, int part_
 
     // Make request headers
     for(auto iter = meta.cbegin(); iter != meta.cend(); ++iter){
-        std::string key   = lower(iter->first);
+        auto key          = CaseInsensitiveStringView(iter->first);
         const auto& value = iter->second;
         if(key == "x-amz-copy-source"){
             requestHeaders = curl_slist_sort_insert(requestHeaders, iter->first.c_str(), value.c_str());
diff --git a/src/string_util.h b/src/string_util.h
index 0b6b9ca..dc3a41c 100644
--- a/src/string_util.h
+++ b/src/string_util.h
@@ -24,6 +24,7 @@
 #include <cstring>
 #include <ctime>
 #include <string>
+#include <strings.h>
 
 //
 // A collection of string utilities for manipulating URLs and HTTP responses.
@@ -36,6 +37,14 @@ static constexpr char SPACES[] = " \t\r\n";
 //-------------------------------------------------------------------
 // Inline functions
 //-------------------------------------------------------------------
+class CaseInsensitiveStringView {
+public:
+    explicit CaseInsensitiveStringView(const std::string &str) : str(str.c_str()) {}
+    bool operator==(const char *other) const { return strcasecmp(str, other) == 0; }
+    bool is_prefix(const char *prefix) const { return strncasecmp(str, prefix, strlen(prefix)) == 0; }
+private:
+    const char *str;
+};
 static inline bool is_prefix(const char *str, const char *prefix) { return strncmp(str, prefix, strlen(prefix)) == 0; }
 static inline const char* SAFESTRPTR(const char *strptr) { return strptr ? strptr : ""; }