diff --git a/include/uc_priv.h b/include/uc_priv.h
index efff0e7e..c9e19f95 100644
--- a/include/uc_priv.h
+++ b/include/uc_priv.h
@@ -28,7 +28,7 @@ typedef int (*reg_access_t)(uch handle, unsigned int regid, void *value);
 
 typedef void (*reg_reset_t)(uch handle);
 
-typedef bool (*uc_write_mem_t)(AddressSpace *as, hwaddr addr, uint8_t *buf, int len);
+typedef bool (*uc_write_mem_t)(AddressSpace *as, hwaddr addr, const uint8_t *buf, int len);
 
 typedef bool (*uc_read_mem_t)(AddressSpace *as, hwaddr addr, uint8_t *buf, int len);
 
diff --git a/include/unicorn/unicorn.h b/include/unicorn/unicorn.h
index 0063ba5a..d5bb350a 100644
--- a/include/unicorn/unicorn.h
+++ b/include/unicorn/unicorn.h
@@ -303,7 +303,7 @@ uc_err uc_reg_read(uch handle, int regid, void *value);
  for detailed error).
 */
 UNICORN_EXPORT
-uc_err uc_mem_write(uch handle, uint64_t address, uint8_t *bytes, size_t size);
+uc_err uc_mem_write(uch handle, uint64_t address, const uint8_t *bytes, size_t size);
 
 /*
  Read a range of bytes in memory.
diff --git a/qemu/unicorn_common.h b/qemu/unicorn_common.h
index 2a6a0668..93f1c5f4 100644
--- a/qemu/unicorn_common.h
+++ b/qemu/unicorn_common.h
@@ -14,7 +14,7 @@ static inline bool cpu_physical_mem_read(AddressSpace *as, hwaddr addr,
 }
 
 static inline bool cpu_physical_mem_write(AddressSpace *as, hwaddr addr,
-                                            uint8_t *buf, int len)
+                                            const uint8_t *buf, int len)
 {
     return !cpu_physical_memory_rw(as, addr, (void *)buf, len, 1);
 }
diff --git a/regress/Makefile b/regress/Makefile
index 4fcfac82..8f8d2556 100644
--- a/regress/Makefile
+++ b/regress/Makefile
@@ -1,7 +1,7 @@
 CFLAGS += -I../include
 LDFLAGS = -L.. -lunicorn
 
-TESTS = map_crash
+TESTS = map_crash sigill
 
 all: $(TESTS)
 
diff --git a/uc.c b/uc.c
index ec337d36..cef74de1 100644
--- a/uc.c
+++ b/uc.c
@@ -356,7 +356,7 @@ uc_err uc_mem_read(uch handle, uint64_t address, uint8_t *bytes, size_t size)
 
 
 UNICORN_EXPORT
-uc_err uc_mem_write(uch handle, uint64_t address, uint8_t *bytes, size_t size)
+uc_err uc_mem_write(uch handle, uint64_t address, const uint8_t *bytes, size_t size)
 {
     struct uc_struct *uc = (struct uc_struct *)(uintptr_t)handle;