diff --git a/lib/tr46map.h b/lib/tr46map.h
@@ -1,5 +1,5 @@
 /* tr46map.c - header file for IDNA2008 TR46
-   Copyright (C) 2016-2017 Tim Rühsen
+   Copyright (C) 2016-2017 Tim Ruehsen
 
    Libidn2 is free software: you can redistribute it and/or modify it
    under the terms of either:
@@ -26,7 +26,11 @@
    not, see <http://www.gnu.org/licenses/>.
 */
 
+#ifndef LIBIDN2_TR46MAP_H
+#define LIBIDN2_TR46MAP_H
+
 #include <stdint.h>
+#include "idn2.h"
 
 #define TR46_FLG_VALID                   1
 #define TR46_FLG_MAPPED                  2
@@ -51,8 +55,14 @@ typedef struct
   char check;			/* 0=NO 2=MAYBE (YES if codepoint has no table entry) */
 } NFCQCMap;
 
-int get_idna_map (uint32_t c, IDNAMap * map);
-int get_map_data (uint32_t * dst, const IDNAMap * map);
-int map_is (const IDNAMap * map, unsigned flags);
+int
+	get_idna_map (uint32_t c, IDNAMap * map);
+int
+	get_map_data (uint32_t * dst, const IDNAMap * map);
+int G_GNUC_IDN2_ATTRIBUTE_PURE
+	map_is (const IDNAMap * map, unsigned flags);
+
+G_GNUC_IDN2_ATTRIBUTE_PURE NFCQCMap
+	*get_nfcqc_map (uint32_t c);
 
-NFCQCMap *get_nfcqc_map (uint32_t c);
+#endif /* LIBIDN2_TR46MAP_H */
diff --git a/tests/test-lookup.c b/tests/test-lookup.c
@@ -822,7 +822,7 @@ static const struct idna idna[] = {
   {"_443._tcp.example.com", "443.tcp.example.com", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_NONTRANSITIONAL},
   {"_443._tcp.example.com", "443.tcp.example.com", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_TRANSITIONAL},
   {"_443._tcp.example.com", "_443._tcp.example.com", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_NO_TR46}, /* flag is ignored when not using TR46 */
-  /* _��� */
+  /* _??? */
   {"_\xc3\xbc", "xn--_-eha", IDN2_DISALLOWED, IDN2_NO_TR46},
   {"_\xc3\xbc", "xn--_-eha", IDN2_OK, IDN2_TRANSITIONAL},
   {"_\xc3\xbc", "xn--_-eha", IDN2_OK, IDN2_NONTRANSITIONAL},
@@ -839,12 +839,12 @@ static const struct idna idna[] = {
 static int ok = 0, failed = 0;
 static int break_on_error = 0;
 
-static char *_nextField(char **line)
+static const char *_nextField(char **line)
 {
   char *s = *line, *e;
 
   if (!*s)
-    return NULL;
+    return "";
 
   if (!(e = strpbrk(s, ";#"))) {
     e = *line += strlen(s);
@@ -899,7 +899,6 @@ test_homebrewed(void)
 {
   uint32_t dummy_u32[4] = { 'a', 'b', 'c', 0 };
   uint8_t *out;
-  char outbuf[4];
   size_t i;
   int rc;
 
@@ -1033,17 +1032,18 @@ test_homebrewed(void)
     ok++;
   }
 
-  if ((rc = idna_to_ascii_4i (dummy_u32, 4, outbuf, 0)) != IDN2_OK) {
+  if ((rc = idn2_to_ascii_4i2 (dummy_u32, 4, (char **) &out, 0)) != IDN2_OK) {
     failed++;
     printf("special #9 failed with %d\n", rc);
   } else {
+    idn2_free (out);
     ok++;
   }
 }
 
 // decode embedded UTF-16/32 sequences
-static char *
-_decodeIdnaTest(uint8_t *src_u8)
+static uint8_t *
+_decodeIdnaTest(const uint8_t *src_u8)
 {
   size_t it2 = 0, len;
   uint32_t *src;
@@ -1088,19 +1088,16 @@ _decodeIdnaTest(uint8_t *src_u8)
   }
 
   // convert UTF-32 to UTF-8
-  uint8_t *tmp=src_u8;
-  src_u8 = u32_to_u8(src, it2, NULL, &len);
-  free(src);
-  if (!src_u8) {
-    printf("u32_to_u8(%s) failed (%d)\n", tmp, errno);
-    return NULL;
-  }
+  uint8_t *dst_u8 = u32_to_u8(src, it2, NULL, &len);
+  if (!dst_u8)
+    printf("u32_to_u8(%s) failed (%d)\n", src_u8, errno);
 
-  return (char *) src_u8;
+  free(src);
+  return dst_u8;
 }
 
 static void
-_check_toASCII(char *source, char *expected, int transitional, int expected_toASCII_failure)
+_check_toASCII(const char *source, const char *expected, int transitional, int expected_toASCII_failure)
 {
   int rc;
   char *ace = NULL;
@@ -1133,18 +1130,19 @@ _check_toASCII(char *source, char *expected, int transitional, int expected_toAS
 static int
 test_IdnaTest(char *linep)
 {
-  char *type, *source, *toUnicode, *toASCII, *NV8, *org_source;
+  char *source;
+  const char *type, *toUnicode, *toASCII, *NV8, *org_source;
   int expected_toASCII_failure;
 
   type = _nextField(&linep);
-  org_source = source = _nextField(&linep);
+  org_source = _nextField(&linep);
   toUnicode = _nextField(&linep);
   toASCII = _nextField(&linep);
   NV8 = _nextField(&linep); // if set, the input should be disallowed for IDNA2008
 
   // sigh, these Unicode people really mix UTF-8 and UCS-2/4
   // quick and dirty translation of '\uXXXX' found in IdnaTest.txt including surrogate handling
-  source = _decodeIdnaTest((uint8_t *) source);
+  source = (char *) _decodeIdnaTest((uint8_t *) org_source);
   if (!source)
     return 0; // some Unicode sequences can't be encoded into UTF-8, skip them
 

diff --git a/tests/test-strerror.c b/tests/test-strerror.c
@@ -19,7 +19,7 @@
 
 #include <idn2.h>
 
-int
+int G_GNUC_IDN2_ATTRIBUTE_CONST
 main (void)
 {
   int i, failed = 0;

diff --git a/tests/test-tounicode.c b/tests/test-tounicode.c
@@ -383,7 +383,7 @@ ucs4print (const uint32_t * str, size_t len)
     printf ("\n");
 }
 
-static size_t
+static size_t G_GNUC_IDN2_ATTRIBUTE_PURE
 _u32_strlen(const uint32_t *s)
 {
   const uint32_t *e;
@@ -394,7 +394,7 @@ _u32_strlen(const uint32_t *s)
   return e - s;
 }
 
-static size_t
+static size_t G_GNUC_IDN2_ATTRIBUTE_PURE
 _u32_strcmp(const uint32_t *s1, const uint32_t *s2)
 {
   while (*s1 && *s2 && *s1 == *s2)