diff --git a/Makefile b/Makefile
index f41ccb0..3a5d60a 100644
--- a/Makefile
+++ b/Makefile
@@ -79,11 +79,12 @@ READELF   = $(CROSS_COMPILE)readelf
 INC_PATH += $(WORK_DIR)/include $(addsuffix /include/, $(addprefix $(AM_HOME)/, $(LIBS)))
 INCFLAGS += $(addprefix -I, $(INC_PATH))
 
+ARCH_H := arch/$(ARCH).h
 CFLAGS   += -O2 -MMD -Wall -Werror $(INCFLAGS) \
             -D__ISA__=\"$(ISA)\" -D__ISA_$(shell echo $(ISA) | tr a-z A-Z)__ \
             -D__ARCH__=$(ARCH) -D__ARCH_$(shell echo $(ARCH) | tr a-z A-Z | tr - _) \
             -D__PLATFORM__=$(PLATFORM) -D__PLATFORM_$(shell echo $(PLATFORM) | tr a-z A-Z | tr - _) \
-            -DARCH_H=\"arch/$(ARCH).h\" \
+            -DARCH_H=\"$(ARCH_H)\" \
             -fno-asynchronous-unwind-tables -fno-builtin -fno-stack-protector \
             -Wno-main -U_FORTIFY_SOURCE
 CXXFLAGS +=  $(CFLAGS) -ffreestanding -fno-rtti -fno-exceptions
diff --git a/am/include/arch/riscv32-nemu.h b/am/include/arch/riscv.h
similarity index 83%
rename from am/include/arch/riscv32-nemu.h
rename to am/include/arch/riscv.h
index 29eaea2..9c9de20 100644
--- a/am/include/arch/riscv32-nemu.h
+++ b/am/include/arch/riscv.h
@@ -7,7 +7,12 @@ struct Context {
   void *pdir;
 };
 
+#ifdef __riscv_e
+#define GPR1 gpr[15] // a5
+#else
 #define GPR1 gpr[17] // a7
+#endif
+
 #define GPR2 gpr[0]
 #define GPR3 gpr[0]
 #define GPR4 gpr[0]
diff --git a/am/include/arch/riscv64-nemu.h b/am/include/arch/riscv64-nemu.h
deleted file mode 100644
index 8a3fb4e..0000000
--- a/am/include/arch/riscv64-nemu.h
+++ /dev/null
@@ -1,15 +0,0 @@
-#ifndef ARCH_H__
-#define ARCH_H__
-
-struct Context {
-  // TODO: fix the order of these members to match trap.S
-  uintptr_t mepc, mcause, gpr[32], mstatus;
-  void *pdir;
-};
-
-#define GPR1 gpr[17] // a7
-#define GPR2 gpr[0]
-#define GPR3 gpr[0]
-#define GPR4 gpr[0]
-#define GPRx gpr[0]
-#endif
diff --git a/am/include/arch/riscv64-npc.h b/am/include/arch/riscv64-npc.h
deleted file mode 100644
index d28ce47..0000000
--- a/am/include/arch/riscv64-npc.h
+++ /dev/null
@@ -1,14 +0,0 @@
-#ifndef ARCH_H__
-#define ARCH_H__
-
-struct Context {
-  // TODO: fix the order of these members to match trap.S
-  uintptr_t mepc, mcause, gpr[32], mstatus;
-};
-
-#define GPR1 gpr[17] // a7
-#define GPR2 gpr[0]
-#define GPR3 gpr[0]
-#define GPR4 gpr[0]
-#define GPRx gpr[0]
-#endif
diff --git a/am/include/arch/spike.h b/am/include/arch/spike.h
deleted file mode 100644
index ea47a63..0000000
--- a/am/include/arch/spike.h
+++ /dev/null
@@ -1,14 +0,0 @@
-#ifndef ARCH_H__
-#define ARCH_H__
-
-struct Context {
-  uintptr_t gpr[1];
-};
-
-#define GPR1 gpr[0]
-#define GPR2 gpr[0]
-#define GPR3 gpr[0]
-#define GPR4 gpr[0]
-#define GPRx gpr[0]
-
-#endif
diff --git a/scripts/isa/riscv.mk b/scripts/isa/riscv.mk
index adcc44f..e478842 100644
--- a/scripts/isa/riscv.mk
+++ b/scripts/isa/riscv.mk
@@ -3,3 +3,6 @@ COMMON_CFLAGS := -fno-pic -march=rv64g -mcmodel=medany -mstrict-align
 CFLAGS        += $(COMMON_CFLAGS) -static
 ASFLAGS       += $(COMMON_CFLAGS) -O0
 LDFLAGS       += -melf64lriscv
+
+# overwrite ARCH_H defined in $(AM_HOME)/Makefile
+ARCH_H := arch/riscv.h