diff --git a/tests/test-registrable-domain.c b/tests/test-registrable-domain.c
index c075500..715498c 100644
--- a/tests/test-registrable-domain.c
+++ b/tests/test-registrable-domain.c
@@ -38,6 +38,11 @@
 #include <ctype.h>
 #include <alloca.h>
 
+#ifdef WITH_LIBICU
+#	include <unicode/uversion.h>
+#	include <unicode/ustring.h>
+#endif
+
 #include <libpsl.h>
 
 static int
@@ -61,6 +66,26 @@ static void test(const psl_ctx_t *psl, const char *domain, const char *expected_
 		/* if we found utf-8, make sure to convert domain correctly to lowercase */
 		/* does it work, if we are not in a utf-8 env ? */
 		if (utf8) {
+#ifdef WITH_LIBICU
+			UErrorCode status = 0;
+			UChar utf16_dst[64], utf16_src[64];
+			int32_t utf16_src_length;
+
+			/* UTF-8 to lowercase conversion */
+			u_strFromUTF8(utf16_src, sizeof(utf16_src)/sizeof(utf16_src[0]), &utf16_src_length, domain, (int32_t) strlen(domain), &status);
+			if (U_SUCCESS(status)) {
+				int32_t dst_length = u_strToLower(utf16_dst, sizeof(utf16_dst)/sizeof(utf16_dst[0]), utf16_src, -1, "en", &status);
+				if (U_SUCCESS(status)) {
+					u_strToUTF8(lookupname, (int32_t) sizeof(lookupname), NULL, utf16_dst, dst_length, &status);
+					if (U_SUCCESS(status)) {
+						domain = lookupname;
+					} else
+						fprintf(stderr, "Failed to convert UTF-16 to UTF-8 (status %d)\n", status);
+				} else
+					fprintf(stderr, "Failed to convert to ASCII (status %d)\n", status);
+			} else
+				fprintf(stderr, "Failed to convert UTF-8 to UTF-16 (status %d)\n", status);
+#else
 			FILE *pp;
 			size_t cmdsize = 48 + strlen(domain);
 			char *cmd = alloca(cmdsize);
@@ -71,6 +96,7 @@ static void test(const psl_ctx_t *psl, const char *domain, const char *expected_
 					domain = lookupname;
 				pclose(pp);
 			}
+#endif
 		}
 	}