diff --git a/src/input/plugins/CurlInputPlugin.cxx b/src/input/plugins/CurlInputPlugin.cxx
index 9fc1710d5..60d3df8c1 100644
--- a/src/input/plugins/CurlInputPlugin.cxx
+++ b/src/input/plugins/CurlInputPlugin.cxx
@@ -36,6 +36,7 @@
 #include "event/Loop.hxx"
 #include "util/ASCII.hxx"
 #include "util/StringFormat.hxx"
+#include "util/StringView.hxx"
 #include "util/NumberParser.hxx"
 #include "util/Domain.hxx"
 #include "Log.hxx"
diff --git a/src/tag/ReplayGain.cxx b/src/tag/ReplayGain.cxx
index bd8d65fda..72fbd54d4 100644
--- a/src/tag/ReplayGain.cxx
+++ b/src/tag/ReplayGain.cxx
@@ -22,6 +22,7 @@
 #include "ReplayGainInfo.hxx"
 #include "util/ASCII.hxx"
 #include "util/NumberParser.hxx"
+#include "util/StringView.hxx"
 
 #include <cassert>
 
diff --git a/src/tag/Table.cxx b/src/tag/Table.cxx
index 4e1bd4958..188cd58bc 100644
--- a/src/tag/Table.cxx
+++ b/src/tag/Table.cxx
@@ -19,6 +19,7 @@
 
 #include "Table.hxx"
 #include "util/ASCII.hxx"
+#include "util/StringView.hxx"
 
 #include <string.h>
 
diff --git a/src/util/ASCII.hxx b/src/util/ASCII.hxx
index ad063db77..df51d8650 100644
--- a/src/util/ASCII.hxx
+++ b/src/util/ASCII.hxx
@@ -30,10 +30,10 @@
 #ifndef ASCII_HXX
 #define ASCII_HXX
 
-#include "StringView.hxx"
 #include "Compiler.h"
 
 #include <cassert>
+#include <string_view>
 
 #include <strings.h>
 
@@ -73,17 +73,19 @@ StringEqualsCaseASCII(const char *a, const char *b, size_t n) noexcept
 
 gcc_pure gcc_nonnull_all
 static inline bool
-StringStartsWithCaseASCII(const char *haystack, StringView needle) noexcept
+StringStartsWithCaseASCII(const char *haystack,
+			  std::string_view needle) noexcept
 {
-	return StringEqualsCaseASCII(haystack, needle.data, needle.size);
+	return StringEqualsCaseASCII(haystack, needle.data(), needle.length());
 }
 
 gcc_pure gcc_nonnull_all
 static inline const char *
-StringAfterPrefixCaseASCII(const char *haystack, StringView needle) noexcept
+StringAfterPrefixCaseASCII(const char *haystack,
+			   std::string_view needle) noexcept
 {
 	return StringStartsWithCaseASCII(haystack, needle)
-		? haystack + needle.size
+		? haystack + needle.length()
 		: nullptr;
 }