diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9d9fb17b35..870f129e5f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,6 +23,10 @@ jobs:
             variant: host
             arch: Host
             toolchain: clang
+          - os: ubuntu-latest
+            variant: host
+            arch: Host
+            toolchain: gcc64
           - variant: rp2040
             arch: Rp2040
 
@@ -36,6 +40,7 @@ jobs:
       SMING_ARCH: ${{ matrix.arch }}
       SMING_SOC: ${{ matrix.variant }}
       CLANG_BUILD: ${{ matrix.toolchain == 'clang' && '15' || '0' }}
+      BUILD64: ${{ matrix.toolchain == 'gcc64' && 1 || 0 }}
 
     steps:
     - name: Fix autocrlf setting
diff --git a/Sming/Arch/Host/README.rst b/Sming/Arch/Host/README.rst
index 92718875e0..9acb1ca446 100644
--- a/Sming/Arch/Host/README.rst
+++ b/Sming/Arch/Host/README.rst
@@ -71,6 +71,13 @@ Configuration
    Note: This setting is not 'sticky'
 
 
+.. envvar:: BUILD64
+
+   default: undefined
+
+   Set to 1 to build in native 64-bit mode.
+
+
 Components
 ----------
 
diff --git a/Sming/Arch/Host/app.mk b/Sming/Arch/Host/app.mk
index 4af8f3fe53..940dc9a4d9 100644
--- a/Sming/Arch/Host/app.mk
+++ b/Sming/Arch/Host/app.mk
@@ -5,9 +5,9 @@
 ###
 
 # linker flags used to generate the main object file
-LDFLAGS += \
-	-m32
-
+ifneq ($(BUILD64),1)
+LDFLAGS += -m32
+endif
 
 # Executable
 TARGET_OUT_0			:= $(FW_BASE)/$(APP_NAME)$(TOOL_EXT)
diff --git a/Sming/Arch/Host/build.mk b/Sming/Arch/Host/build.mk
index 2129b2e506..f14bb481b5 100644
--- a/Sming/Arch/Host/build.mk
+++ b/Sming/Arch/Host/build.mk
@@ -41,8 +41,11 @@ GDB		:= $(TOOLSPEC)gdb
 
 GCC_UPGRADE_URL := https://sming.readthedocs.io/en/latest/arch/host/host-emulator.html\#c-c-32-bit-compiler-and-libraries
 
+ifneq ($(BUILD64),1)
+CPPFLAGS += -m32
+endif
+
 CPPFLAGS += \
-	-m32 \
 	-D_FILE_OFFSET_BITS=64 \
 	-D_TIME_BITS=64
 
diff --git a/Sming/Components/FlashString b/Sming/Components/FlashString
index a44b584a10..f2f3a40163 160000
--- a/Sming/Components/FlashString
+++ b/Sming/Components/FlashString
@@ -1 +1 @@
-Subproject commit a44b584a100848fdb89cc6ea5f1778b4557d3227
+Subproject commit f2f3a401634c393ffdde8e5ce73b0fb88a625b33
diff --git a/Sming/Components/Storage/component.mk b/Sming/Components/Storage/component.mk
index eb711a1054..70fb882817 100644
--- a/Sming/Components/Storage/component.mk
+++ b/Sming/Components/Storage/component.mk
@@ -3,6 +3,9 @@ COMPONENT_SRCDIRS	:= src
 COMPONENT_DOXYGEN_INPUT := src/include
 
 COMPONENT_VARS := ENABLE_STORAGE_SIZE64
+ifeq ($(BUILD64),1)
+override ENABLE_STORAGE_SIZE64 := 1
+endif
 ifeq ($(ENABLE_STORAGE_SIZE64),1)
 GLOBAL_CFLAGS += -DENABLE_STORAGE_SIZE64
 endif
diff --git a/Sming/Components/axtls-8266/axtls-8266.patch b/Sming/Components/axtls-8266/axtls-8266.patch
index 19688134c4..9311810b10 100644
--- a/Sming/Components/axtls-8266/axtls-8266.patch
+++ b/Sming/Components/axtls-8266/axtls-8266.patch
@@ -731,7 +731,7 @@ index 5bd2394..5363d22 100644
      if (memcmp(mac, orig_mac, SHA1_SIZE))
      {
 diff --git a/ssl/tls1.c b/ssl/tls1.c
-index 8f0fbfb..b2dcddd 100644
+index 8f0fbfb..f099e2c 100644
 --- a/ssl/tls1.c
 +++ b/ssl/tls1.c
 @@ -85,7 +85,7 @@ static const cipher_info_t cipher_info[NUM_PROTOCOLS] =
@@ -914,6 +914,15 @@ index 8f0fbfb..b2dcddd 100644
  #endif
              ret = SSL_ERROR_NOT_SUPPORTED;
              goto error; /* not an error - just get out of here */
+@@ -1432,7 +1436,7 @@ int basic_read(SSL *ssl, uint8_t **in_data)
+         /* is the allocated buffer large enough to handle all the data? if not, increase its size*/
+         if (ssl->need_bytes > ssl->max_plain_length+RT_EXTRA-BM_RECORD_OFFSET)
+         {
+-            printf("ssl->need_bytes=%d > %d\r\n", ssl->need_bytes, ssl->max_plain_length+RT_EXTRA-BM_RECORD_OFFSET);
++            printf("ssl->need_bytes=%u > %u\r\n", ssl->need_bytes, (unsigned)ssl->max_plain_length+RT_EXTRA-BM_RECORD_OFFSET);
+             ret = increase_bm_data_size(ssl, ssl->need_bytes + BM_RECORD_OFFSET - RT_EXTRA);
+             if (ret != SSL_OK)
+             {
 @@ -1562,7 +1566,7 @@ int increase_bm_data_size(SSL *ssl, size_t size)
      required = (required < RT_MAX_PLAIN_LENGTH) ? required : RT_MAX_PLAIN_LENGTH;
      uint8_t* new_bm_all_data = (uint8_t*) realloc(ssl->bm_all_data, required + RT_EXTRA);
diff --git a/Sming/Components/lwip/component.mk b/Sming/Components/lwip/component.mk
index c6d48d82a8..b692dcf685 100644
--- a/Sming/Components/lwip/component.mk
+++ b/Sming/Components/lwip/component.mk
@@ -38,6 +38,9 @@ endif
 ifeq ($(SMING_RELEASE),1)
 	LWIP_CMAKE_OPTIONS	+= -DLWIP_NOASSERT=1
 endif
+ifneq ($(BUILD64),1)
+	LWIP_CMAKE_OPTIONS	+= -DBUILD_MODE=-m32
+endif
 
 LWIP_TARGET := $(COMPONENT_LIBDIR)/lib$(LWIP_LIBNAME).a
 COMPONENT_TARGETS += $(LWIP_TARGET)
diff --git a/Sming/Components/lwip/src/Arch/Host/Linux/CMakeLists.txt b/Sming/Components/lwip/src/Arch/Host/Linux/CMakeLists.txt
index 19ba30ac35..a4a9c4e6a7 100644
--- a/Sming/Components/lwip/src/Arch/Host/Linux/CMakeLists.txt
+++ b/Sming/Components/lwip/src/Arch/Host/Linux/CMakeLists.txt
@@ -37,6 +37,6 @@ set_target_properties(lwip
 	PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${USER_LIBDIR} OUTPUT_NAME "${LWIP_LIBNAME}"
 )
 
-target_compile_options(lwip PRIVATE ${LWIP_COMPILER_FLAGS} -m32)
+target_compile_options(lwip PRIVATE ${LWIP_COMPILER_FLAGS} ${BUILD_MODE})
 target_compile_definitions(lwip PRIVATE ${LWIP_DEFINITIONS} ${LWIP_MBEDTLS_DEFINITIONS})
 target_include_directories(lwip PRIVATE ${LWIP_INCLUDE_DIRS} ${LWIP_MBEDTLS_INCLUDE_DIRS})
diff --git a/Sming/Core/DateTime.cpp b/Sming/Core/DateTime.cpp
index 688d1ee3ed..57b20d23d5 100644
--- a/Sming/Core/DateTime.cpp
+++ b/Sming/Core/DateTime.cpp
@@ -17,7 +17,7 @@
 #if defined(__WIN32) || (defined(ARCH_ESP32) && ESP_IDF_VERSION_MAJOR < 5)
 static_assert(sizeof(time_t) != 8, "Great! Now supports 64-bit - please update code");
 #warning "**Y2038** time_t is only 32-bits in this build configuration"
-#elif defined(ARCH_HOST) && !defined(__USE_TIME_BITS64)
+#elif defined(ARCH_HOST) && __TIMESIZE != 64 && !defined(__USE_TIME_BITS64)
 #warning "**Y2038** Expecting 64-bit time_t - please use GCC 10 or later"
 #else
 static_assert(sizeof(time_t) == 8, "Expecting 64-bit time_t - please use GCC 10 or later");
diff --git a/Sming/Libraries/CsvReader b/Sming/Libraries/CsvReader
index 8f4d416442..8d441afdf8 160000
--- a/Sming/Libraries/CsvReader
+++ b/Sming/Libraries/CsvReader
@@ -1 +1 @@
-Subproject commit 8f4d416442292927d15fe00d80130fb2fc7d8bb6
+Subproject commit 8d441afdf80c40265a29d2bddc6cad64ea0f128c
diff --git a/Sming/Libraries/jerryscript b/Sming/Libraries/jerryscript
index 21ac3e053d..f355d307de 160000
--- a/Sming/Libraries/jerryscript
+++ b/Sming/Libraries/jerryscript
@@ -1 +1 @@
-Subproject commit 21ac3e053d2a63ebc1955f2a62c2978c7447e119
+Subproject commit f355d307de19bc3f498d2edb4ac945cccfb4b5d2
diff --git a/Sming/Wiring/WString.h b/Sming/Wiring/WString.h
index f6c5a689ac..915cbf5926 100644
--- a/Sming/Wiring/WString.h
+++ b/Sming/Wiring/WString.h
@@ -804,7 +804,8 @@ class String
 	float toFloat(void) const;
 
 	/// Max chars. (excluding NUL terminator) we can store in SSO mode
-	static constexpr size_t SSO_CAPACITY = STRING_OBJECT_SIZE - 2;
+	static constexpr size_t SSO_SIZE = std::max(size_t(STRING_OBJECT_SIZE), sizeof(char*) * 3);
+	static constexpr size_t SSO_CAPACITY = SSO_SIZE - 2;
 
 protected:
 	/// Used when contents allocated on heap
@@ -824,10 +825,10 @@ class String
 		SsoBuf sso;
 	};
 
-	static_assert(STRING_OBJECT_SIZE == sizeof(SsoBuf), "SSO Buffer alignment problem");
-	static_assert(STRING_OBJECT_SIZE >= sizeof(PtrBuf), "STRING_OBJECT_SIZE too small");
-	static_assert(STRING_OBJECT_SIZE <= 128, "STRING_OBJECT_SIZE too large (max. 128)");
-	static_assert(STRING_OBJECT_SIZE % 4 == 0, "STRING_OBJECT_SIZE must be a multiple of 4");
+	static_assert(SSO_SIZE == sizeof(SsoBuf), "SSO Buffer alignment problem");
+	static_assert(SSO_SIZE >= sizeof(PtrBuf), "STRING_OBJECT_SIZE too small");
+	static_assert(SSO_SIZE <= 128, "STRING_OBJECT_SIZE too large (max. 128)");
+	static_assert(SSO_SIZE % 4 == 0, "STRING_OBJECT_SIZE must be a multiple of 4");
 
 protected:
 	// Free any heap memory and set to non-SSO mode; isNull() will return true
diff --git a/Sming/build.mk b/Sming/build.mk
index c932ff78cd..0253b8dbb7 100644
--- a/Sming/build.mk
+++ b/Sming/build.mk
@@ -140,6 +140,13 @@ DEBUG_VARS += AWK
 # invokes an awk compatibility mode. It has no effect on other awk implementations.
 AWK ?= POSIXLY_CORRECT= awk
 
+DEBUG_VARS += SED
+ifeq ($(UNAME),Darwin)
+SED ?= gsed
+else
+SED ?= sed
+endif
+
 # Python command
 DEBUG_VARS += PYTHON
 ifdef PYTHON
diff --git a/Sming/component-wrapper.mk b/Sming/component-wrapper.mk
index 88aca58d41..ee82818afb 100644
--- a/Sming/component-wrapper.mk
+++ b/Sming/component-wrapper.mk
@@ -112,7 +112,7 @@ CXXFLAGS	+= $(COMPONENT_CXXFLAGS)
 
 # GCC 10 escapes ':' in path names which breaks GNU make for Windows so filter them
 ifeq ($(UNAME),Windows)
-OUTPUT_DEPS := | sed "s/\\\\:/:/g" > $$@
+OUTPUT_DEPS := | $(SED) "s/\\\\:/:/g" > $$@
 else
 OUTPUT_DEPS := -MF $$@
 endif
diff --git a/Sming/project.mk b/Sming/project.mk
index cf928ea1b0..e1830fca6a 100644
--- a/Sming/project.mk
+++ b/Sming/project.mk
@@ -19,7 +19,7 @@ endif
 
 .PHONY: all
 all: checksoc checkdirs submodules ##(default) Build all Component libraries
-	$(MAKE) components application
+	$(Q) $(MAKE) components application
 
 # Load current build type from file
 BUILD_TYPE_FILE	:= out/build-type.mk
diff --git a/tests/HostTests/modules/CStringArray.cpp b/tests/HostTests/modules/CStringArray.cpp
index bb640bf83f..c149aa59df 100644
--- a/tests/HostTests/modules/CStringArray.cpp
+++ b/tests/HostTests/modules/CStringArray.cpp
@@ -239,24 +239,22 @@ class CStringArrayTest : public TestGroup
 
 		TEST_CASE("release")
 		{
-			CStringArray csa(FS_Basic);
-			csa += FS_Basic; // Allocate > SSO
+			String orig;
+			// Allocate > SSO
+			while(orig.length() <= String::SSO_CAPACITY) {
+				orig += FS_Basic;
+			}
+			CStringArray csa = orig;
 			Serial << csa.join() << endl;
 			auto cstrWant = csa.c_str();
 			String s = csa.release();
 			REQUIRE(!csa);
 			REQUIRE(s.c_str() == cstrWant);
 
-			REQUIRE(s == String(FS_Basic) + FS_Basic);
+			REQUIRE(s == orig);
 
 			csa = std::move(s);
-			REQUIRE(csa == String(FS_Basic) + FS_Basic);
-
-			String js;
-			js += FS_BasicJoined;
-			js += ',';
-			js += FS_BasicJoined;
-			REQUIRE(csa.join() == js);
+			REQUIRE(csa == orig);
 		}
 	}
 };