diff --git a/port/cpl_vsil_adls.cpp b/port/cpl_vsil_adls.cpp
index 3e701b2f1960..d37f64a23d0b 100644
--- a/port/cpl_vsil_adls.cpp
+++ b/port/cpl_vsil_adls.cpp
@@ -165,7 +165,8 @@ class VSIADLSFSHandler final : public IVSIS3LikeFSHandlerWithMultipartUpload
 
   protected:
     VSICurlHandle *CreateFileHandle(const char *pszFilename) override;
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     char **GetFileList(const char *pszFilename, int nMaxFiles,
                        bool *pbGotFileList) override;
@@ -1268,18 +1269,17 @@ void VSIADLSFSHandler::ClearCache()
 /*                          GetURLFromFilename()                        */
 /************************************************************************/
 
-std::string VSIADLSFSHandler::GetURLFromFilename(const std::string &osFilename)
+std::string
+VSIADLSFSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
-    std::string osFilenameWithoutPrefix =
+    const std::string osFilenameWithoutPrefix =
         osFilename.substr(GetFSPrefix().size());
-    VSIAzureBlobHandleHelper *poHandleHelper =
+    auto poHandleHelper = std::unique_ptr<VSIAzureBlobHandleHelper>(
         VSIAzureBlobHandleHelper::BuildFromURI(osFilenameWithoutPrefix.c_str(),
-                                               GetFSPrefix().c_str());
-    if (poHandleHelper == nullptr)
+                                               GetFSPrefix().c_str()));
+    if (!poHandleHelper)
         return std::string();
-    std::string osURL(poHandleHelper->GetURLNoKVP());
-    delete poHandleHelper;
-    return osURL;
+    return poHandleHelper->GetURLNoKVP();
 }
 
 /************************************************************************/
diff --git a/port/cpl_vsil_az.cpp b/port/cpl_vsil_az.cpp
index fe1924dc03c2..cce23faf875d 100644
--- a/port/cpl_vsil_az.cpp
+++ b/port/cpl_vsil_az.cpp
@@ -509,7 +509,8 @@ class VSIAzureFSHandler final : public IVSIS3LikeFSHandlerWithMultipartUpload
 
   protected:
     VSICurlHandle *CreateFileHandle(const char *pszFilename) override;
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     VSIAzureBlobHandleHelper *CreateAzHandleHelper(const char *pszURI,
                                                    bool bAllowNoObject);
@@ -1423,18 +1424,17 @@ void VSIAzureFSHandler::ClearCache()
 /*                          GetURLFromFilename()                        */
 /************************************************************************/
 
-std::string VSIAzureFSHandler::GetURLFromFilename(const std::string &osFilename)
+std::string
+VSIAzureFSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
     std::string osFilenameWithoutPrefix =
         osFilename.substr(GetFSPrefix().size());
-    VSIAzureBlobHandleHelper *poHandleHelper =
+    auto poHandleHelper = std::unique_ptr<VSIAzureBlobHandleHelper>(
         VSIAzureBlobHandleHelper::BuildFromURI(osFilenameWithoutPrefix.c_str(),
-                                               GetFSPrefix().c_str());
-    if (poHandleHelper == nullptr)
+                                               GetFSPrefix().c_str()));
+    if (!poHandleHelper)
         return std::string();
-    std::string osURL(poHandleHelper->GetURLNoKVP());
-    delete poHandleHelper;
-    return osURL;
+    return poHandleHelper->GetURLNoKVP();
 }
 
 /************************************************************************/
diff --git a/port/cpl_vsil_curl.cpp b/port/cpl_vsil_curl.cpp
index 237c7eb17319..692073e23cb4 100644
--- a/port/cpl_vsil_curl.cpp
+++ b/port/cpl_vsil_curl.cpp
@@ -4771,8 +4771,8 @@ static bool VSICurlParseFullFTPLine(char *pszLine, char *&pszFilename,
 /*                          GetURLFromFilename()                         */
 /************************************************************************/
 
-std::string
-VSICurlFilesystemHandlerBase::GetURLFromFilename(const std::string &osFilename)
+std::string VSICurlFilesystemHandlerBase::GetURLFromFilename(
+    const std::string &osFilename) const
 {
     return VSICurlGetURLFromFilename(osFilename.c_str(), nullptr, nullptr,
                                      nullptr, nullptr, nullptr, nullptr,
diff --git a/port/cpl_vsil_curl_class.h b/port/cpl_vsil_curl_class.h
index 90120b069f2c..7691c4927f68 100644
--- a/port/cpl_vsil_curl_class.h
+++ b/port/cpl_vsil_curl_class.h
@@ -333,7 +333,7 @@ class VSICurlFilesystemHandlerBase : public VSIFilesystemHandler
     void SetCachedDirList(const char *pszURL, CachedDirList &oCachedDirList);
     bool ExistsInCacheDirList(const std::string &osDirname, bool *pbIsDir);
 
-    virtual std::string GetURLFromFilename(const std::string &osFilename);
+    virtual std::string GetURLFromFilename(const std::string &osFilename) const;
 
     std::string
     GetStreamingFilename(const std::string &osFilename) const override = 0;
diff --git a/port/cpl_vsil_gs.cpp b/port/cpl_vsil_gs.cpp
index e8350cb2ea87..46faa2f9a929 100644
--- a/port/cpl_vsil_gs.cpp
+++ b/port/cpl_vsil_gs.cpp
@@ -83,7 +83,8 @@ class VSIGSFSHandler final : public IVSIS3LikeFSHandlerWithMultipartUpload
         return m_osPrefix;
     }
 
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     IVSIS3LikeHandleHelper *CreateHandleHelper(const char *pszURI,
                                                bool bAllowNoObject) override;
@@ -292,17 +293,17 @@ char *VSIGSFSHandler::GetSignedURL(const char *pszFilename,
 /*                          GetURLFromFilename()                         */
 /************************************************************************/
 
-std::string VSIGSFSHandler::GetURLFromFilename(const std::string &osFilename)
+std::string
+VSIGSFSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
-    std::string osFilenameWithoutPrefix =
+    const std::string osFilenameWithoutPrefix =
         osFilename.substr(GetFSPrefix().size());
-    VSIGSHandleHelper *poHandleHelper = VSIGSHandleHelper::BuildFromURI(
-        osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str());
+    auto poHandleHelper =
+        std::unique_ptr<VSIGSHandleHelper>(VSIGSHandleHelper::BuildFromURI(
+            osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str()));
     if (poHandleHelper == nullptr)
         return std::string();
-    std::string osURL(poHandleHelper->GetURL());
-    delete poHandleHelper;
-    return osURL;
+    return poHandleHelper->GetURL();
 }
 
 /************************************************************************/
diff --git a/port/cpl_vsil_oss.cpp b/port/cpl_vsil_oss.cpp
index e2e20a699fae..d4ea4639b927 100644
--- a/port/cpl_vsil_oss.cpp
+++ b/port/cpl_vsil_oss.cpp
@@ -68,7 +68,8 @@ class VSIOSSFSHandler final : public IVSIS3LikeFSHandlerWithMultipartUpload
 
   protected:
     VSICurlHandle *CreateFileHandle(const char *pszFilename) override;
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     const char *GetDebugKey() const override
     {
@@ -235,26 +236,26 @@ VSICurlHandle *VSIOSSFSHandler::CreateFileHandle(const char *pszFilename)
 }
 
 /************************************************************************/
-/*                          GetURLFromFilename()                         */
+/*                          GetURLFromFilename()                        */
 /************************************************************************/
 
-std::string VSIOSSFSHandler::GetURLFromFilename(const std::string &osFilename)
+std::string
+VSIOSSFSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
-    std::string osFilenameWithoutPrefix =
+    const std::string osFilenameWithoutPrefix =
         osFilename.substr(GetFSPrefix().size());
 
-    VSIOSSHandleHelper *poHandleHelper = VSIOSSHandleHelper::BuildFromURI(
-        osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str(), true);
-    if (poHandleHelper == nullptr)
+    auto poHandleHelper =
+        std::unique_ptr<VSIOSSHandleHelper>(VSIOSSHandleHelper::BuildFromURI(
+            osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str(), true));
+    if (!poHandleHelper)
     {
-        return "";
+        return std::string();
     }
 
     std::string osBaseURL(poHandleHelper->GetURL());
     if (!osBaseURL.empty() && osBaseURL.back() == '/')
-        osBaseURL.resize(osBaseURL.size() - 1);
-    delete poHandleHelper;
-
+        osBaseURL.pop_back();
     return osBaseURL;
 }
 
diff --git a/port/cpl_vsil_s3.cpp b/port/cpl_vsil_s3.cpp
index 5225e45b9f1e..39304b44661d 100644
--- a/port/cpl_vsil_s3.cpp
+++ b/port/cpl_vsil_s3.cpp
@@ -645,7 +645,8 @@ class VSIS3FSHandler final : public IVSIS3LikeFSHandlerWithMultipartUpload
 
   protected:
     VSICurlHandle *CreateFileHandle(const char *pszFilename) override;
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     const char *GetDebugKey() const override
     {
@@ -2825,22 +2826,22 @@ VSICurlHandle *VSIS3FSHandler::CreateFileHandle(const char *pszFilename)
 /*                          GetURLFromFilename()                         */
 /************************************************************************/
 
-std::string VSIS3FSHandler::GetURLFromFilename(const std::string &osFilename)
+std::string
+VSIS3FSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
-    std::string osFilenameWithoutPrefix =
+    const std::string osFilenameWithoutPrefix =
         osFilename.substr(GetFSPrefix().size());
 
-    VSIS3HandleHelper *poS3HandleHelper = VSIS3HandleHelper::BuildFromURI(
-        osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str(), true);
-    if (poS3HandleHelper == nullptr)
+    auto poS3HandleHelper =
+        std::unique_ptr<VSIS3HandleHelper>(VSIS3HandleHelper::BuildFromURI(
+            osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str(), true));
+    if (!poS3HandleHelper)
     {
-        return "";
+        return std::string();
     }
     std::string osBaseURL(poS3HandleHelper->GetURL());
     if (!osBaseURL.empty() && osBaseURL.back() == '/')
-        osBaseURL.resize(osBaseURL.size() - 1);
-    delete poS3HandleHelper;
-
+        osBaseURL.pop_back();
     return osBaseURL;
 }
 
diff --git a/port/cpl_vsil_swift.cpp b/port/cpl_vsil_swift.cpp
index 6cddce26fffe..40edc5619d38 100644
--- a/port/cpl_vsil_swift.cpp
+++ b/port/cpl_vsil_swift.cpp
@@ -212,7 +212,8 @@ class VSISwiftFSHandler final : public IVSIS3LikeFSHandler
 
   protected:
     VSICurlHandle *CreateFileHandle(const char *pszFilename) override;
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     const char *GetDebugKey() const override
     {
@@ -385,22 +386,22 @@ VSICurlHandle *VSISwiftFSHandler::CreateFileHandle(const char *pszFilename)
 /*                         GetURLFromFilename()                         */
 /************************************************************************/
 
-std::string VSISwiftFSHandler::GetURLFromFilename(const std::string &osFilename)
+std::string
+VSISwiftFSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
-    std::string osFilenameWithoutPrefix =
+    const std::string osFilenameWithoutPrefix =
         osFilename.substr(GetFSPrefix().size());
 
-    VSISwiftHandleHelper *poHandleHelper = VSISwiftHandleHelper::BuildFromURI(
-        osFilenameWithoutPrefix.c_str(), GetFSPrefix().c_str());
-    if (poHandleHelper == nullptr)
+    auto poHandleHelper = std::unique_ptr<VSISwiftHandleHelper>(
+        VSISwiftHandleHelper::BuildFromURI(osFilenameWithoutPrefix.c_str(),
+                                           GetFSPrefix().c_str()));
+    if (!poHandleHelper)
     {
-        return "";
+        return std::string();
     }
     std::string osBaseURL(poHandleHelper->GetURL());
     if (!osBaseURL.empty() && osBaseURL.back() == '/')
-        osBaseURL.resize(osBaseURL.size() - 1);
-    delete poHandleHelper;
-
+        osBaseURL.pop_back();
     return osBaseURL;
 }
 
diff --git a/port/cpl_vsil_webhdfs.cpp b/port/cpl_vsil_webhdfs.cpp
index be4fa10eb500..d94fce3da7f8 100644
--- a/port/cpl_vsil_webhdfs.cpp
+++ b/port/cpl_vsil_webhdfs.cpp
@@ -81,7 +81,8 @@ class VSIWebHDFSFSHandler final : public VSICurlFilesystemHandlerBaseWritable
     char **GetFileList(const char *pszFilename, int nMaxFiles,
                        bool *pbGotFileList) override;
 
-    std::string GetURLFromFilename(const std::string &osFilename) override;
+    std::string
+    GetURLFromFilename(const std::string &osFilename) const override;
 
     VSIVirtualHandleUniquePtr
     CreateWriteHandle(const char *pszFilename,
@@ -564,11 +565,11 @@ VSICurlHandle *VSIWebHDFSFSHandler::CreateFileHandle(const char *pszFilename)
 }
 
 /************************************************************************/
-/*                          GetURLFromFilename()                         */
+/*                          GetURLFromFilename()                        */
 /************************************************************************/
 
 std::string
-VSIWebHDFSFSHandler::GetURLFromFilename(const std::string &osFilename)
+VSIWebHDFSFSHandler::GetURLFromFilename(const std::string &osFilename) const
 {
     return osFilename.substr(GetFSPrefix().size());
 }