diff --git a/test/test_base64_RFC2152_decoder.cpp b/test/test_base64_RFC2152_decoder.cpp
index f1ff542e..e7f1cc3e 100644
--- a/test/test_base64_RFC2152_decoder.cpp
+++ b/test/test_base64_RFC2152_decoder.cpp
@@ -32,20 +32,16 @@ SOFTWARE.
 
 #include "etl/base64_decoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-2152
 //*****************************************************************************
diff --git a/test/test_base64_RFC2152_encoder.cpp b/test/test_base64_RFC2152_encoder.cpp
index 07e5b9a3..cfeb62f9 100644
--- a/test/test_base64_RFC2152_encoder.cpp
+++ b/test/test_base64_RFC2152_encoder.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_encoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-2152 with no padding
 // Using minimum buffer size, with callback.
diff --git a/test/test_base64_RFC3501_decoder.cpp b/test/test_base64_RFC3501_decoder.cpp
index 7dc5baec..75439d63 100644
--- a/test/test_base64_RFC3501_decoder.cpp
+++ b/test/test_base64_RFC3501_decoder.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_decoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-3501
 //*****************************************************************************
diff --git a/test/test_base64_RFC3501_encoder.cpp b/test/test_base64_RFC3501_encoder.cpp
index 57a4f3a1..032057b5 100644
--- a/test/test_base64_RFC3501_encoder.cpp
+++ b/test/test_base64_RFC3501_encoder.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_encoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-3501 with no padding
 // Using minimum buffer size, with callback.
diff --git a/test/test_base64_RFC4648_URL_decoder_with_no_padding.cpp b/test/test_base64_RFC4648_URL_decoder_with_no_padding.cpp
index 16bc0935..c0abb3bd 100644
--- a/test/test_base64_RFC4648_URL_decoder_with_no_padding.cpp
+++ b/test/test_base64_RFC4648_URL_decoder_with_no_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_decoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648-URL with no padding
 //*****************************************************************************
diff --git a/test/test_base64_RFC4648_URL_decoder_with_padding.cpp b/test/test_base64_RFC4648_URL_decoder_with_padding.cpp
index d7cc35d3..d99758ed 100644
--- a/test/test_base64_RFC4648_URL_decoder_with_padding.cpp
+++ b/test/test_base64_RFC4648_URL_decoder_with_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_decoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648-URL with no padding
 //*****************************************************************************
diff --git a/test/test_base64_RFC4648_URL_encoder_with_no_padding.cpp b/test/test_base64_RFC4648_URL_encoder_with_no_padding.cpp
index c1cb2b9c..3c32c94f 100644
--- a/test/test_base64_RFC4648_URL_encoder_with_no_padding.cpp
+++ b/test/test_base64_RFC4648_URL_encoder_with_no_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_encoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648-URL with no padding
 // Using minimum buffer size, with callback.
diff --git a/test/test_base64_RFC4648_URL_encoder_with_padding.cpp b/test/test_base64_RFC4648_URL_encoder_with_padding.cpp
index 4bb21b13..f1327786 100644
--- a/test/test_base64_RFC4648_URL_encoder_with_padding.cpp
+++ b/test/test_base64_RFC4648_URL_encoder_with_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_encoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648-URL with padding
 // Using minimum buffer size, with callback.
diff --git a/test/test_base64_RFC4648_decoder_with_no_padding.cpp b/test/test_base64_RFC4648_decoder_with_no_padding.cpp
index 77533716..0e31ee4e 100644
--- a/test/test_base64_RFC4648_decoder_with_no_padding.cpp
+++ b/test/test_base64_RFC4648_decoder_with_no_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_decoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648 with no padding
 //*****************************************************************************
diff --git a/test/test_base64_RFC4648_decoder_with_padding.cpp b/test/test_base64_RFC4648_decoder_with_padding.cpp
index f4cd0c4a..54d0f2fc 100644
--- a/test/test_base64_RFC4648_decoder_with_padding.cpp
+++ b/test/test_base64_RFC4648_decoder_with_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_decoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648 with no padding
 //*****************************************************************************
diff --git a/test/test_base64_RFC4648_encoder_with_no_padding.cpp b/test/test_base64_RFC4648_encoder_with_no_padding.cpp
index d925b4d8..d71b44b1 100644
--- a/test/test_base64_RFC4648_encoder_with_no_padding.cpp
+++ b/test/test_base64_RFC4648_encoder_with_no_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_encoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648 with no padding
 // Using minimum buffer size, with callback.
diff --git a/test/test_base64_RFC4648_encoder_with_padding.cpp b/test/test_base64_RFC4648_encoder_with_padding.cpp
index f40fc733..92c63c0f 100644
--- a/test/test_base64_RFC4648_encoder_with_padding.cpp
+++ b/test/test_base64_RFC4648_encoder_with_padding.cpp
@@ -30,20 +30,16 @@ SOFTWARE.
 
 #include "etl/base64_encoder.h"
 
+#include "etl/integral_limits.h"
 #include "etl/string.h"
 #include "etl/vector.h"
 
 #include <algorithm>
 #include <array>
+#include <iterator>
 #include <string>
 #include <vector>
 
-#if ETL_USING_STL
-  #include <iterator>
-#endif
-
-#include "etl/integral_limits.h"
-
 //*****************************************************************************
 // Encode/decode using RFC-4648 with padding
 // Using minimum buffer size, with callback.
diff --git a/test/test_circular_buffer.cpp b/test/test_circular_buffer.cpp
index 34452537..2bbf9feb 100644
--- a/test/test_circular_buffer.cpp
+++ b/test/test_circular_buffer.cpp
@@ -67,7 +67,7 @@ namespace
       CHECK(data.crbegin() == data.crend());
     }
 
-#if ETL_USING_STL
+#if ETL_HAS_INITIALIZER_LIST
     //*************************************************************************
     TEST(test_constructor_from_literal)
     {
diff --git a/test/test_circular_buffer_external_buffer.cpp b/test/test_circular_buffer_external_buffer.cpp
index a1374986..cd0c40cd 100644
--- a/test/test_circular_buffer_external_buffer.cpp
+++ b/test/test_circular_buffer_external_buffer.cpp
@@ -99,7 +99,7 @@ namespace
       CHECK(data.crbegin() == data.crend());
     }
 
-#if ETL_USING_STL
+#if ETL_HAS_INITIALIZER_LIST
     //*************************************************************************
     TEST(test_constructor_from_literal)
     {
diff --git a/test/test_message_router_registry.cpp b/test/test_message_router_registry.cpp
index 22da80cb..17e27797 100644
--- a/test/test_message_router_registry.cpp
+++ b/test/test_message_router_registry.cpp
@@ -187,7 +187,7 @@ namespace
       CHECK_EQUAL(Registry_Size, registry.max_size());
     }
 
-#if ETL_USING_STL
+#if ETL_HAS_INITIALIZER_LIST
     //*************************************************************************
     TEST(test_initializer_list_construction)
     {
diff --git a/test/test_numeric.cpp b/test/test_numeric.cpp
index f7407fef..8251a27c 100644
--- a/test/test_numeric.cpp
+++ b/test/test_numeric.cpp
@@ -135,7 +135,6 @@ namespace
       CHECK_EQUAL(*c, v);
     }
 
-#if ETL_USING_STL
     //*************************************************************************
     TEST(test_midpoint_std_random_access_iterator)
     {
@@ -163,7 +162,6 @@ namespace
 
       CHECK_EQUAL(*c, v);
     }
-#endif
 
     //*************************************************************************
     TEST(test_lerp_floating_point)
diff --git a/test/test_ranges.cpp b/test/test_ranges.cpp
index cab77148..f7a668fe 100644
--- a/test/test_ranges.cpp
+++ b/test/test_ranges.cpp
@@ -41,7 +41,7 @@ SOFTWARE.
 
 // Issue #1391: include <ranges> when available to verify etl::operator|
 // does not conflict with std::ranges::operator|.
-#if ETL_USING_STL && ETL_USING_CPP20 && defined(__has_include)
+#if ETL_USING_CPP20 && defined(__has_include)
   #if __has_include(<ranges>)
     #include <ranges>
   #endif
diff --git a/test/test_type_traits.cpp b/test/test_type_traits.cpp
index 603c992b..531557de 100644
--- a/test/test_type_traits.cpp
+++ b/test/test_type_traits.cpp
@@ -759,6 +759,7 @@ namespace
       CHECK(etl::is_fundamental<long double>::value == std::is_fundamental<long double>::value);
       CHECK(etl::is_fundamental<Test>::value == std::is_fundamental<Test>::value);
 #if ETL_USING_STL
+      // etl::is_fundamental does not report std::nullptr_t as fundamental when not using the STL.
       CHECK(etl::is_fundamental<std::nullptr_t>::value == std::is_fundamental<std::nullptr_t>::value);
 #endif
     }