diff --git a/src/lib/icu/Util.cxx b/src/lib/icu/Util.cxx
index 74904dd09..34076f398 100644
--- a/src/lib/icu/Util.cxx
+++ b/src/lib/icu/Util.cxx
@@ -31,18 +31,15 @@
 #include <string.h>
 
 AllocatedArray<UChar>
-UCharFromUTF8(const char *src)
+UCharFromUTF8(std::string_view src)
 {
-	assert(src != nullptr);
-
-	const size_t src_length = strlen(src);
-	const size_t dest_capacity = src_length;
+	const size_t dest_capacity = src.size();
 	AllocatedArray<UChar> dest(dest_capacity);
 
 	UErrorCode error_code = U_ZERO_ERROR;
 	int32_t dest_length;
 	u_strFromUTF8(dest.begin(), dest_capacity, &dest_length,
-		      src, src_length,
+		      src.data(), src.size(),
 		      &error_code);
 	if (U_FAILURE(error_code))
 		throw std::runtime_error(u_errorName(error_code));
@@ -52,19 +49,17 @@ UCharFromUTF8(const char *src)
 }
 
 AllocatedString<>
-UCharToUTF8(ConstBuffer<UChar> src)
+UCharToUTF8(std::basic_string_view<UChar> src)
 {
-	assert(!src.IsNull());
-
 	/* worst-case estimate */
-	size_t dest_capacity = 4 * src.size;
+	size_t dest_capacity = 4 * src.size();
 
 	std::unique_ptr<char[]> dest(new char[dest_capacity + 1]);
 
 	UErrorCode error_code = U_ZERO_ERROR;
 	int32_t dest_length;
 	u_strToUTF8(dest.get(), dest_capacity, &dest_length,
-		    src.data, src.size,
+		    src.data(), src.size(),
 		    &error_code);
 	if (U_FAILURE(error_code))
 		throw std::runtime_error(u_errorName(error_code));
diff --git a/src/lib/icu/Util.hxx b/src/lib/icu/Util.hxx
index 89ce3e597..4d71cf066 100644
--- a/src/lib/icu/Util.hxx
+++ b/src/lib/icu/Util.hxx
@@ -22,7 +22,8 @@
 
 #include <unicode/utypes.h>
 
-template<typename T> struct ConstBuffer;
+#include <string_view>
+
 template<typename T> class AllocatedArray;
 template<typename T> class AllocatedString;
 
@@ -32,7 +33,7 @@ template<typename T> class AllocatedString;
  * Throws std::runtime_error on error.
  */
 AllocatedArray<UChar>
-UCharFromUTF8(const char *src);
+UCharFromUTF8(std::string_view src);
 
 /**
  * Wrapper for u_strToUTF8().
@@ -40,6 +41,6 @@ UCharFromUTF8(const char *src);
  * Throws std::runtime_error on error.
  */
 AllocatedString<char>
-UCharToUTF8(ConstBuffer<UChar> src);
+UCharToUTF8(std::basic_string_view<UChar> src);
 
 #endif