diff --git a/src/lib/curl/Adapter.cxx b/src/lib/curl/Adapter.cxx
index 89595566e..3beade3d0 100644
--- a/src/lib/curl/Adapter.cxx
+++ b/src/lib/curl/Adapter.cxx
@@ -112,8 +112,10 @@ IsResponseBoundaryHeader(StringView s) noexcept
 }
 
 inline void
-CurlResponseHandlerAdapter::HeaderFunction(StringView s) noexcept
+CurlResponseHandlerAdapter::HeaderFunction(std::string_view _s) noexcept
 {
+	const StringView s{_s};
+
 	if (state > State::HEADERS)
 		return;
 
diff --git a/src/lib/curl/Adapter.hxx b/src/lib/curl/Adapter.hxx
index fc4c946c3..40c174425 100644
--- a/src/lib/curl/Adapter.hxx
+++ b/src/lib/curl/Adapter.hxx
@@ -34,8 +34,8 @@
 #include <curl/curl.h>
 
 #include <cstddef>
+#include <string_view>
 
-struct StringView;
 class CurlEasy;
 class CurlResponseHandler;
 
@@ -68,7 +68,7 @@ private:
 	void FinishHeaders();
 	void FinishBody();
 
-	void HeaderFunction(StringView s) noexcept;
+	void HeaderFunction(std::string_view s) noexcept;
 
 	/** called by curl when a new header is available */
 	static std::size_t _HeaderFunction(char *ptr,
diff --git a/src/lib/curl/Request.hxx b/src/lib/curl/Request.hxx
index fcd68ca8e..26386afc4 100644
--- a/src/lib/curl/Request.hxx
+++ b/src/lib/curl/Request.hxx
@@ -35,7 +35,6 @@
 
 #include <cstddef>
 
-struct StringView;
 class CurlGlobal;
 class CurlResponseHandler;