diff --git a/gio/tests/contenttype.c b/gio/tests/contenttype.c
index 2424b8e5f..b860a1dac 100644
--- a/gio/tests/contenttype.c
+++ b/gio/tests/contenttype.c
@@ -39,7 +39,7 @@ test_guess (void)
   g_free (existing_directory);
   expected = g_content_type_from_mime_type ("inode/directory");
   g_assert_content_type_equals (expected, res);
-  g_assert (uncertain);
+  g_assert_true (uncertain);
   g_free (res);
   g_free (expected);
 
@@ -52,7 +52,7 @@ test_guess (void)
   res = g_content_type_guess ("foo.txt", data, sizeof (data) - 1, &uncertain);
   expected = g_content_type_from_mime_type ("text/plain");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 
@@ -61,21 +61,21 @@ test_guess (void)
   res = g_content_type_guess ("foo", data, sizeof (data) - 1, &uncertain);
   expected = g_content_type_from_mime_type ("text/plain");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 
   res = g_content_type_guess ("foo.desktop", data, sizeof (data) - 1, &uncertain);
   expected = g_content_type_from_mime_type ("application/x-desktop");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 
   res = g_content_type_guess (NULL, data, sizeof (data) - 1, &uncertain);
   expected = g_content_type_from_mime_type ("application/x-desktop");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 
@@ -84,14 +84,14 @@ test_guess (void)
   res = g_content_type_guess ("test.pot", (guchar *)"ABC abc", 7, &uncertain);
   expected = g_content_type_from_mime_type ("text/x-gettext-translation-template");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 
   res = g_content_type_guess ("test.pot", (guchar *)"msgid \"", 7, &uncertain);
   expected = g_content_type_from_mime_type ("text/x-gettext-translation-template");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 
@@ -107,7 +107,7 @@ test_guess (void)
   res = g_content_type_guess ("test.otf", (guchar *)"OTTO", 4, &uncertain);
   expected = g_content_type_from_mime_type ("application/x-font-otf");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 #endif
@@ -115,7 +115,7 @@ test_guess (void)
   res = g_content_type_guess (NULL, (guchar *)"%!PS-Adobe-2.0 EPSF-1.2", 23, &uncertain);
   expected = g_content_type_from_mime_type ("image/x-eps");
   g_assert_content_type_equals (expected, res);
-  g_assert (!uncertain);
+  g_assert_false (uncertain);
   g_free (res);
   g_free (expected);
 }
@@ -127,7 +127,7 @@ test_unknown (void)
   gchar *str;
 
   unknown = g_content_type_from_mime_type ("application/octet-stream");
-  g_assert (g_content_type_is_unknown (unknown));
+  g_assert_true (g_content_type_is_unknown (unknown));
   str = g_content_type_get_mime_type (unknown);
   g_assert_cmpstr (str, ==, "application/octet-stream");
   g_free (str);
@@ -143,8 +143,8 @@ test_subtype (void)
   plain = g_content_type_from_mime_type ("text/plain");
   xml = g_content_type_from_mime_type ("application/xml");
 
-  g_assert (g_content_type_is_a (xml, plain));
-  g_assert (g_content_type_is_mime_type (xml, "text/plain"));
+  g_assert_true (g_content_type_is_a (xml, plain));
+  g_assert_true (g_content_type_is_mime_type (xml, "text/plain"));
 
   g_free (plain);
   g_free (xml);
@@ -175,11 +175,11 @@ test_list (void)
 
   types = g_content_types_get_registered ();
 
-  g_assert (g_list_length (types) > 1);
+  g_assert_cmpuint (g_list_length (types), >, 1);
 
   /* just check that some types are in the list */
-  g_assert (g_list_find_custom (types, plain, find_mime) != NULL);
-  g_assert (g_list_find_custom (types, xml, find_mime) != NULL);
+  g_assert_nonnull (g_list_find_custom (types, plain, find_mime));
+  g_assert_nonnull (g_list_find_custom (types, xml, find_mime));
 
   g_list_free_full (types, g_free);
 
@@ -193,15 +193,15 @@ test_executable (void)
   gchar *type;
 
   type = g_content_type_from_mime_type ("application/x-executable");
-  g_assert (g_content_type_can_be_executable (type));
+  g_assert_true (g_content_type_can_be_executable (type));
   g_free (type);
 
   type = g_content_type_from_mime_type ("text/plain");
-  g_assert (g_content_type_can_be_executable (type));
+  g_assert_true (g_content_type_can_be_executable (type));
   g_free (type);
 
   type = g_content_type_from_mime_type ("image/png");
-  g_assert (!g_content_type_can_be_executable (type));
+  g_assert_false (g_content_type_can_be_executable (type));
   g_free (type);
 }
 
@@ -213,7 +213,7 @@ test_description (void)
 
   type = g_content_type_from_mime_type ("text/plain");
   desc = g_content_type_get_description (type);
-  g_assert (desc != NULL);
+  g_assert_nonnull (desc);
 
   g_free (desc);
   g_free (type);
@@ -227,17 +227,17 @@ test_icon (void)
 
   type = g_content_type_from_mime_type ("text/plain");
   icon = g_content_type_get_icon (type);
-  g_assert (G_IS_ICON (icon));
+  g_assert_true (G_IS_ICON (icon));
   if (G_IS_THEMED_ICON (icon))
     {
       const gchar *const *names;
 
       names = g_themed_icon_get_names (G_THEMED_ICON (icon));
 #ifdef __APPLE__
-      g_assert (g_strv_contains (names, "text-*"));
+      g_assert_true (g_strv_contains (names, "text-*"));
 #else
-      g_assert (g_strv_contains (names, "text-plain"));
-      g_assert (g_strv_contains (names, "text-x-generic"));
+      g_assert_true (g_strv_contains (names, "text-plain"));
+      g_assert_true (g_strv_contains (names, "text-x-generic"));
 #endif
     }
   g_object_unref (icon);
@@ -245,15 +245,15 @@ test_icon (void)
 
   type = g_content_type_from_mime_type ("application/rtf");
   icon = g_content_type_get_icon (type);
-  g_assert (G_IS_ICON (icon));
+  g_assert_true (G_IS_ICON (icon));
   if (G_IS_THEMED_ICON (icon))
     {
       const gchar *const *names;
 
       names = g_themed_icon_get_names (G_THEMED_ICON (icon));
-      g_assert (g_strv_contains (names, "application-rtf"));
+      g_assert_true (g_strv_contains (names, "application-rtf"));
 #ifndef __APPLE__
-      g_assert (g_strv_contains (names, "x-office-document"));
+      g_assert_true (g_strv_contains (names, "x-office-document"));
 #endif
     }
   g_object_unref (icon);
@@ -269,20 +269,20 @@ test_symbolic_icon (void)
 
   type = g_content_type_from_mime_type ("text/plain");
   icon = g_content_type_get_symbolic_icon (type);
-  g_assert (G_IS_ICON (icon));
+  g_assert_true (G_IS_ICON (icon));
   if (G_IS_THEMED_ICON (icon))
     {
       const gchar *const *names;
 
       names = g_themed_icon_get_names (G_THEMED_ICON (icon));
 #ifdef __APPLE__
-      g_assert (g_strv_contains (names, "text-*-symbolic"));
-      g_assert (g_strv_contains (names, "text-*"));
+      g_assert_true (g_strv_contains (names, "text-*-symbolic"));
+      g_assert_true (g_strv_contains (names, "text-*"));
 #else
-      g_assert (g_strv_contains (names, "text-plain-symbolic"));
-      g_assert (g_strv_contains (names, "text-x-generic-symbolic"));
-      g_assert (g_strv_contains (names, "text-plain"));
-      g_assert (g_strv_contains (names, "text-x-generic"));
+      g_assert_true (g_strv_contains (names, "text-plain-symbolic"));
+      g_assert_true (g_strv_contains (names, "text-x-generic-symbolic"));
+      g_assert_true (g_strv_contains (names, "text-plain"));
+      g_assert_true (g_strv_contains (names, "text-x-generic"));
 #endif
     }
   g_object_unref (icon);
@@ -290,17 +290,17 @@ test_symbolic_icon (void)
 
   type = g_content_type_from_mime_type ("application/rtf");
   icon = g_content_type_get_symbolic_icon (type);
-  g_assert (G_IS_ICON (icon));
+  g_assert_true (G_IS_ICON (icon));
   if (G_IS_THEMED_ICON (icon))
     {
       const gchar *const *names;
 
       names = g_themed_icon_get_names (G_THEMED_ICON (icon));
-      g_assert (g_strv_contains (names, "application-rtf-symbolic"));
-      g_assert (g_strv_contains (names, "application-rtf"));
+      g_assert_true (g_strv_contains (names, "application-rtf-symbolic"));
+      g_assert_true (g_strv_contains (names, "application-rtf"));
 #ifndef __APPLE__
-      g_assert (g_strv_contains (names, "x-office-document-symbolic"));
-      g_assert (g_strv_contains (names, "x-office-document"));
+      g_assert_true (g_strv_contains (names, "x-office-document-symbolic"));
+      g_assert_true (g_strv_contains (names, "x-office-document"));
 #endif
     }
   g_object_unref (icon);