diff --git a/Makefile b/Makefile
index c2541332..5631c2f5 100644
--- a/Makefile
+++ b/Makefile
@@ -180,7 +180,7 @@ CFLAGS+=$(WOLFPSA_CFLAGS)
 
 # Setup default optimizations (for GCC)
 ifeq ($(USE_GCC_HEADLESS),1)
-  CFLAGS+=-Wall -Wextra -Wno-main -ffreestanding -nostartfiles
+  CFLAGS+=-Wall -Wextra -Wno-main -ffreestanding
   CFLAGS+=-ffunction-sections -fdata-sections -fomit-frame-pointer
   # Allow unused parameters and functions
   CFLAGS+=-Wno-unused-parameter -Wno-unused-function
diff --git a/arch.mk b/arch.mk
index 849fa036..570cf3b2 100644
--- a/arch.mk
+++ b/arch.mk
@@ -134,8 +134,12 @@ endif
 ifeq ($(ARCH),ARM)
   CROSS_COMPILE?=arm-none-eabi-
   CFLAGS+=-DARCH_ARM
-  CFLAGS+=-mthumb -mlittle-endian -mthumb-interwork
-  LDFLAGS+=-mthumb -mlittle-endian -mthumb-interwork
+  CFLAGS+=-mthumb -mlittle-endian
+  LDFLAGS+=-mthumb -mlittle-endian
+  ifeq ($(USE_GCC),1)
+    CFLAGS+=-mthumb-interwork
+    LDFLAGS+=-mthumb-interwork
+  endif
 
   ## Target specific configuration
   ifeq ($(TARGET),samr21)
diff --git a/include/wolfboot/wolfboot.h b/include/wolfboot/wolfboot.h
index f7b5fdb0..33d29923 100644
--- a/include/wolfboot/wolfboot.h
+++ b/include/wolfboot/wolfboot.h
@@ -46,7 +46,11 @@ extern "C" {
 #ifndef RAMFUNCTION
 #  if defined(__WOLFBOOT) && defined(RAM_CODE)
 #    if defined(ARCH_ARM)
-#      define RAMFUNCTION __attribute__((used,section(".ramcode"),long_call))
+#      if defined(__clang__)
+#        define RAMFUNCTION __attribute__((used,section(".ramcode")))
+#      else
+#        define RAMFUNCTION __attribute__((used,section(".ramcode"),long_call))
+#      endif
 #    elif defined(ARCH_PPC)
 #      define RAMFUNCTION __attribute__((used,section(".ramcode"),longcall))
 #    else
diff --git a/options.mk b/options.mk
index 108e330a..c9884eed 100644
--- a/options.mk
+++ b/options.mk
@@ -1030,9 +1030,11 @@ CFLAGS+=$(CFLAGS_EXTRA)
 OBJS+=$(OBJS_EXTRA)
 
 ifeq ($(USE_GCC_HEADLESS),1)
-  ifneq ($(ARCH),RENESAS_RX)
-    ifneq ($(ARCH),AURIX_TC3)
-      CFLAGS+="-Wstack-usage=$(STACK_USAGE)"
+  ifeq ($(USE_GCC),1)
+    ifneq ($(ARCH),RENESAS_RX)
+      ifneq ($(ARCH),AURIX_TC3)
+        CFLAGS+="-Wstack-usage=$(STACK_USAGE)"
+      endif
     endif
   endif
 endif
diff --git a/src/update_flash.c b/src/update_flash.c
index 3927df33..e3c4de3a 100644
--- a/src/update_flash.c
+++ b/src/update_flash.c
@@ -754,7 +754,7 @@ out:
 
 
 #ifdef WOLFBOOT_ARMORED
-#    ifdef __GNUC__
+#    if defined(__GNUC__) && !defined(__clang__)
 #        pragma GCC push_options
 #        pragma GCC optimize("O0")
 #    elif defined(__IAR_SYSTEMS_ICC__)
@@ -1474,7 +1474,7 @@ void RAMFUNCTION wolfBoot_start(void)
 }
 
 #ifdef WOLFBOOT_ARMORED
-#    ifdef __GNUC__
+#    if defined(__GNUC__) && !defined(__clang__)
 #        pragma GCC pop_options
 #    elif defined(__IAR_SYSTEMS_ICC__)
 #        pragma optimize=default