diff --git a/test/test.c b/test/test.c
index 7bd1565..fbf91eb 100644
--- a/test/test.c
+++ b/test/test.c
@@ -259,3 +259,14 @@ UTEST(c, Near) {
 }
 
 UTEST(c, Todo) { UTEST_SKIP("Not yet implemented!"); }
+
+// TODO: TCC cannot handle comparing null opaque structs at all.
+#if !defined(__TINYC__)
+struct Opaque;
+
+UTEST(c, Opaque) {
+  struct Opaque *opaque = NULL;
+  EXPECT_EQ(NULL, opaque);
+  ASSERT_EQ(NULL, opaque);
+}
+#endif
diff --git a/test/test11.c b/test/test11.c
index c27c0cc..17f844b 100644
--- a/test/test11.c
+++ b/test/test11.c
@@ -251,3 +251,14 @@ UTEST(c11, Near) {
 }
 
 UTEST(c11, Todo) { UTEST_SKIP("Not yet implemented!"); }
+
+// TODO: TCC cannot handle comparing null opaque structs at all.
+#if !defined(__TINYC__)
+struct Opaque;
+
+UTEST(c11, Opaque) {
+  struct Opaque *opaque = NULL;
+  EXPECT_EQ(NULL, opaque);
+  ASSERT_EQ(NULL, opaque);
+}
+#endif
diff --git a/test/test11.cpp b/test/test11.cpp
index 67e8bcd..130eeed 100644
--- a/test/test11.cpp
+++ b/test/test11.cpp
@@ -343,3 +343,20 @@ UTEST(cpp11, Null) {
 }
 
 #endif
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
+#endif
+
+struct Opaque;
+
+UTEST(cpp11, Opaque) {
+  struct Opaque *opaque = nullptr;
+  EXPECT_EQ(nullptr, opaque);
+  ASSERT_EQ(nullptr, opaque);
+}
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
diff --git a/test/test14.cpp b/test/test14.cpp
index 7e16797..a11f834 100644
--- a/test/test14.cpp
+++ b/test/test14.cpp
@@ -343,3 +343,20 @@ UTEST(cpp14, Null) {
 }
 
 #endif
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
+#endif
+
+struct Opaque;
+
+UTEST(cpp14, Opaque) {
+  struct Opaque *opaque = nullptr;
+  EXPECT_EQ(nullptr, opaque);
+  ASSERT_EQ(nullptr, opaque);
+}
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
diff --git a/test/test17.cpp b/test/test17.cpp
index 3c09afa..84b58c1 100644
--- a/test/test17.cpp
+++ b/test/test17.cpp
@@ -343,3 +343,20 @@ UTEST(cpp17, Null) {
 }
 
 #endif
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
+#endif
+
+struct Opaque;
+
+UTEST(cpp17, Opaque) {
+  struct Opaque *opaque = nullptr;
+  EXPECT_EQ(nullptr, opaque);
+  ASSERT_EQ(nullptr, opaque);
+}
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
diff --git a/test/test99.c b/test/test99.c
index 6f1d75a..30a9279 100644
--- a/test/test99.c
+++ b/test/test99.c
@@ -251,3 +251,14 @@ UTEST(c99, Near) {
 }
 
 UTEST(c99, Todo) { UTEST_SKIP("Not yet implemented!"); }
+
+// TODO: TCC cannot handle comparing null opaque structs at all.
+#if !defined(__TINYC__)
+struct Opaque;
+
+UTEST(c99, Opaque) {
+  struct Opaque *opaque = NULL;
+  EXPECT_EQ(NULL, opaque);
+  ASSERT_EQ(NULL, opaque);
+}
+#endif
diff --git a/utest.h b/utest.h
index 5dc25b1..88c119d 100644
--- a/utest.h
+++ b/utest.h
@@ -674,9 +674,7 @@ utest_type_printer(long long unsigned int i) {
 
 #if defined(__cplusplus) && (__cplusplus >= 201103L)
 #define UTEST_AUTO(x) auto
-#elif !defined(__cplusplus)
-
-#if defined(__clang__)
+#elif defined(__clang__)
 /* clang-format off */
 /* had to disable clang-format here because it malforms the pragmas */
 #define UTEST_AUTO(x)                                                          \
@@ -684,14 +682,12 @@ utest_type_printer(long long unsigned int i) {
       _Pragma("clang diagnostic ignored \"-Wgnu-auto-type\"") __auto_type      \
           _Pragma("clang diagnostic pop")
 /* clang-format on */
+#elif !defined(__clang__) && defined(__GNUC__) && !defined(__cplusplus)
+#define UTEST_AUTO(x) __auto_type
 #else
 #define UTEST_AUTO(x) __typeof__(x + 0)
 #endif
 
-#else
-#define UTEST_AUTO(x) typeof(x + 0)
-#endif
-
 #if defined(__clang__)
 #define UTEST_STRNCMP(x, y, size)                                              \
   _Pragma("clang diagnostic push")                                             \