diff --git a/src/builtins.c b/src/builtins.c
index 1533cf4..88d30b1 100644
--- a/src/builtins.c
+++ b/src/builtins.c
@@ -12,7 +12,7 @@ static KrkClass * property;
 FUNC_SIG(list,__init__);
 FUNC_SIG(list,sort);
 
-KrkValue krk_dirObject(int argc, KrkValue argv[], int hasKw) {
+KrkValue krk_dirObject(int argc, const KrkValue argv[], int hasKw) {
 	if (argc != 1)
 		return krk_runtimeError(vm.exceptions->argumentError, "%s() takes %s %d argument%s (%d given)",
 			"dir", "exactly", 1, "", argc);
@@ -679,7 +679,7 @@ KRK_FUNC(issubclass,{
 	}
 })
 
-static KrkValue _module_repr(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _module_repr(int argc, const KrkValue argv[], int hasKw) {
 	KrkInstance * self = AS_INSTANCE(argv[0]);
 
 	KrkValue name = NONE_VAL();
@@ -706,7 +706,7 @@ static KrkValue _module_repr(int argc, KrkValue argv[], int hasKw) {
 	return out;
 }
 
-static KrkValue obj_hash(int argc, KrkValue argv[], int hasKw) {
+static KrkValue obj_hash(int argc, const KrkValue argv[], int hasKw) {
 	KrkObj * self = AS_OBJECT(argv[0]);
 	if (!(self->flags & KRK_OBJ_FLAGS_VALID_HASH)) {
 		self->hash = INTEGER_VAL((int)(intptr_t)self);
@@ -715,7 +715,7 @@ static KrkValue obj_hash(int argc, KrkValue argv[], int hasKw) {
 	return INTEGER_VAL(self->hash);
 }
 
-static KrkValue obj_eq(int argc, KrkValue argv[], int hasKw) {
+static KrkValue obj_eq(int argc, const KrkValue argv[], int hasKw) {
 	return BOOLEAN_VAL(argc == 2 && IS_OBJECT(argv[0]) && IS_OBJECT(argv[1]) && AS_OBJECT(argv[0]) == AS_OBJECT(argv[1]));
 }
 
@@ -732,7 +732,7 @@ static KrkValue obj_eq(int argc, KrkValue argv[], int hasKw) {
  * all types should have a string representation available through
  * those methods.
  */
-static KrkValue _strBase(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _strBase(int argc, const KrkValue argv[], int hasKw) {
 	KrkClass * type = krk_getType(argv[0]);
 
 	KrkValue module = NONE_VAL();
diff --git a/src/exceptions.c b/src/exceptions.c
index 16646bb..e54403b 100644
--- a/src/exceptions.c
+++ b/src/exceptions.c
@@ -26,7 +26,7 @@
  *
  * @param arg Optional string to attach to the exception object.
  */
-static KrkValue krk_initException(int argc, KrkValue argv[], int hasKw) {
+static KrkValue krk_initException(int argc, const KrkValue argv[], int hasKw) {
 	KrkInstance * self = AS_INSTANCE(argv[0]);
 	krk_attachNamedValue(&self->fields, "arg", argc > 1 ? argv[1] : NONE_VAL());
 	return argv[0];
@@ -39,7 +39,7 @@ static KrkValue krk_initException(int argc, KrkValue argv[], int hasKw) {
  *
  * Generates a string representation of the form @c "Exception(arg)" .
  */
-static KrkValue _exception_repr(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _exception_repr(int argc, const KrkValue argv[], int hasKw) {
 	KrkInstance * self = AS_INSTANCE(argv[0]);
 	KrkValue arg;
 	struct StringBuilder sb = {0};
@@ -67,7 +67,7 @@ static KrkValue _exception_repr(int argc, KrkValue argv[], int hasKw) {
  * For most exceptions, this is the 'arg' value attached at initialization
  * and is printed during a traceback after the name of the exception type.
  */
-static KrkValue _exception_str(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _exception_str(int argc, const KrkValue argv[], int hasKw) {
 	KrkInstance * self = AS_INSTANCE(argv[0]);
 	KrkValue arg;
 	if (!krk_tableGet(&self->fields, OBJECT_VAL(S("arg")), &arg) || IS_NONE(arg)) {
@@ -91,7 +91,7 @@ static KrkValue _exception_str(int argc, KrkValue argv[], int hasKw) {
  * {str(Exception)} for syntax errors and they handle the rest. This is a bit
  * of a kludge, but it works for now.
  */
-static KrkValue _syntaxerror_str(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _syntaxerror_str(int argc, const KrkValue argv[], int hasKw) {
 	KrkInstance * self = AS_INSTANCE(argv[0]);
 	/* .arg */
 	KrkValue file, line, lineno, colno, arg, func;
diff --git a/src/kuroko/object.h b/src/kuroko/object.h
index d1a2eb3..0e63f47 100644
--- a/src/kuroko/object.h
+++ b/src/kuroko/object.h
@@ -239,7 +239,7 @@ typedef struct {
 	KrkObj * method;    /**< @brief Function to call */
 } KrkBoundMethod;
 
-typedef KrkValue (*NativeFn)(int argCount, KrkValue* args, int hasKwargs);
+typedef KrkValue (*NativeFn)(int argCount, const KrkValue* args, int hasKwargs);
 
 /**
  * @brief Managed binding to a C function.
diff --git a/src/kuroko/util.h b/src/kuroko/util.h
index e257f36..ccd1322 100644
--- a/src/kuroko/util.h
+++ b/src/kuroko/util.h
@@ -63,14 +63,14 @@
 	ctype name __attribute__((unused)) = AS_ ## type (argv[i])
 
 #define FUNC_NAME(klass, name) _ ## klass ## _ ## name
-#define FUNC_SIG(klass, name) _noexport KrkValue FUNC_NAME(klass,name) (int argc, KrkValue argv[], int hasKw)
+#define FUNC_SIG(klass, name) _noexport KrkValue FUNC_NAME(klass,name) (int argc, const KrkValue argv[], int hasKw)
 #define KRK_METHOD(klass, name, ...) FUNC_SIG(klass, name) { \
 	static __attribute__ ((unused)) const char* _method_name = # name; \
 	CHECK_ARG(0,klass,CURRENT_CTYPE,CURRENT_NAME); \
 	__VA_ARGS__ \
 	return NONE_VAL(); }
 
-#define KRK_FUNC(name,...) static KrkValue _krk_ ## name (int argc, KrkValue argv[], int hasKw) { \
+#define KRK_FUNC(name,...) static KrkValue _krk_ ## name (int argc, const KrkValue argv[], int hasKw) { \
 	static __attribute__ ((unused)) const char* _method_name = # name; \
 	__VA_ARGS__ \
 	return NONE_VAL(); }
@@ -222,11 +222,11 @@ static inline KrkValue discardStringBuilder(struct StringBuilder * sb) {
 #endif
 
 extern KrkValue krk_dict_nth_key_fast(size_t capacity, KrkTableEntry * entries, size_t index);
-extern KrkValue FUNC_NAME(str,__getitem__)(int,KrkValue*,int);
-extern KrkValue FUNC_NAME(str,__int__)(int,KrkValue*,int);
-extern KrkValue FUNC_NAME(str,__float__)(int,KrkValue*,int);
-extern KrkValue FUNC_NAME(str,split)(int,KrkValue*,int);
-extern KrkValue FUNC_NAME(str,format)(int,KrkValue*,int);
+extern KrkValue FUNC_NAME(str,__getitem__)(int,const KrkValue*,int);
+extern KrkValue FUNC_NAME(str,__int__)(int,const KrkValue*,int);
+extern KrkValue FUNC_NAME(str,__float__)(int,const KrkValue*,int);
+extern KrkValue FUNC_NAME(str,split)(int,const KrkValue*,int);
+extern KrkValue FUNC_NAME(str,format)(int,const KrkValue*,int);
 #define krk_string_get FUNC_NAME(str,__getitem__)
 #define krk_string_int FUNC_NAME(str,__int__)
 #define krk_string_float FUNC_NAME(str,__float__)
diff --git a/src/kuroko/vm.h b/src/kuroko/vm.h
index 4710f9e..d89df59 100644
--- a/src/kuroko/vm.h
+++ b/src/kuroko/vm.h
@@ -604,7 +604,7 @@ extern int krk_callValue(KrkValue callee, int argCount, int callableOnStack);
  *
  * This is the native function bound to @c listOf
  */
-extern KrkValue krk_list_of(int argc, KrkValue argv[], int hasKw);
+extern KrkValue krk_list_of(int argc, const KrkValue argv[], int hasKw);
 
 /**
  * @brief Create a dict object.
@@ -612,7 +612,7 @@ extern KrkValue krk_list_of(int argc, KrkValue argv[], int hasKw);
  *
  * This is the native function bound to @c dictOf
  */
-extern KrkValue krk_dict_of(int argc, KrkValue argv[], int hasKw);
+extern KrkValue krk_dict_of(int argc, const KrkValue argv[], int hasKw);
 
 /**
  * @brief Create a tuple object.
@@ -620,7 +620,7 @@ extern KrkValue krk_dict_of(int argc, KrkValue argv[], int hasKw);
  *
  * This is the native function bound to @c tupleOf
  */
-extern KrkValue krk_tuple_of(int argc, KrkValue argv[], int hasKw);
+extern KrkValue krk_tuple_of(int argc, const KrkValue argv[], int hasKw);
 
 /**
  * @brief Create a set object.
@@ -628,13 +628,13 @@ extern KrkValue krk_tuple_of(int argc, KrkValue argv[], int hasKw);
  *
  * This is the native function bound to @c setOf
  */
-extern KrkValue krk_set_of(int argc, KrkValue argv[], int hasKw);
+extern KrkValue krk_set_of(int argc, const KrkValue argv[], int hasKw);
 
 /**
  * @brief Create a slice object.
  * @memberof KrkSlice
  */
-extern KrkValue krk_slice_of(int argc, KrkValue argv[], int hasKw);
+extern KrkValue krk_slice_of(int argc, const KrkValue argv[], int hasKw);
 
 /**
  * @brief Call a callable on the stack with @p argCount arguments.
@@ -720,7 +720,7 @@ extern KrkInstance * krk_startModule(const char * name);
  *
  * This is the native function bound to @c object.__dir__
  */
-extern KrkValue krk_dirObject(int argc, KrkValue argv[], int hasKw);
+extern KrkValue krk_dirObject(int argc, const KrkValue argv[], int hasKw);
 
 /**
  * @brief Load a module from a file with a specified name.
@@ -860,4 +860,4 @@ extern void krk_setMaximumRecursionDepth(size_t maxDepth);
  * held stack is reallocated, it will be freed when execution returns to the call
  * to @c krk_callNativeOnStack that holds it.
  */
-KrkValue krk_callNativeOnStack(NativeFn native, size_t argCount, KrkValue *stackArgs, int hasKw);
+KrkValue krk_callNativeOnStack(NativeFn native, size_t argCount, const KrkValue *stackArgs, int hasKw);
diff --git a/src/modules/module_math.c b/src/modules/module_math.c
index d68ddd1..37281e8 100644
--- a/src/modules/module_math.c
+++ b/src/modules/module_math.c
@@ -17,7 +17,8 @@
 	return NONE_VAL(); \
 }
 
-#define FORCE_FLOAT(arg) \
+#define FORCE_FLOAT(src,arg) \
+	KrkValue arg = src; \
 	if (!IS_FLOATING(arg)) { switch (KRK_VAL_TYPE(arg)) { \
 		case KRK_VAL_INTEGER: arg = FLOATING_VAL(AS_INTEGER(arg)); break; \
 		case KRK_VAL_BOOLEAN: arg = FLOATING_VAL(AS_BOOLEAN(arg)); break; \
@@ -38,7 +39,7 @@
 }
 
 #define MATH_DELEGATE(func) \
-static KrkValue _math_ ## func(int argc, KrkValue argv[], int hasKw) { \
+static KrkValue _math_ ## func(int argc, const KrkValue argv[], int hasKw) { \
 	ONE_ARGUMENT(func) \
 	if (IS_FLOATING(argv[0])) { \
 		return INTEGER_VAL(func(AS_FLOATING(argv[0]))); \
@@ -57,12 +58,12 @@ MATH_DELEGATE(floor)
 MATH_DELEGATE(trunc)
 
 #define MATH_ONE_NAME(func,name) \
-static KrkValue _math_ ## name(int argc, KrkValue argv[], int hasKw) { \
+static KrkValue _math_ ## name(int argc, const KrkValue argv[], int hasKw) { \
 	ONE_ARGUMENT(name) \
-	FORCE_FLOAT(argv[0]) \
-	if (IS_FLOATING(argv[0])) { \
-		return FLOATING_VAL(func(AS_FLOATING(argv[0]))); \
-	} else REAL_NUMBER_NOT(name,argv[0]) \
+	FORCE_FLOAT(argv[0],arg_0) \
+	if (IS_FLOATING(arg_0)) { \
+		return FLOATING_VAL(func(AS_FLOATING(arg_0))); \
+	} else REAL_NUMBER_NOT(name,arg_0) \
 }
 #define MATH_ONE(func) MATH_ONE_NAME(func,func)
 
@@ -93,13 +94,13 @@ MATH_ONE(lgamma)
 #endif
 
 #define MATH_TWO(func) \
-static KrkValue _math_ ## func(int argc, KrkValue argv[], int hasKw) { \
+static KrkValue _math_ ## func(int argc, const KrkValue argv[], int hasKw) { \
 	TWO_ARGUMENTS(func) \
-	FORCE_FLOAT(argv[0]) \
-	FORCE_FLOAT(argv[1]) \
-	if (!IS_FLOATING(argv[0])) REAL_NUMBER_NOT(func,argv[0]) \
-	if (!IS_FLOATING(argv[1])) REAL_NUMBER_NOT(func,argv[1]) \
-	return FLOATING_VAL(func(AS_FLOATING(argv[0]),AS_FLOATING(argv[1]))); \
+	FORCE_FLOAT(argv[0],arg_0) \
+	FORCE_FLOAT(argv[1],arg_1) \
+	if (!IS_FLOATING(arg_0)) REAL_NUMBER_NOT(func,arg_0) \
+	if (!IS_FLOATING(arg_1)) REAL_NUMBER_NOT(func,arg_1) \
+	return FLOATING_VAL(func(AS_FLOATING(arg_0),AS_FLOATING(arg_1))); \
 }
 
 MATH_TWO(copysign)
@@ -108,14 +109,14 @@ MATH_TWO(remainder)
 MATH_TWO(pow)
 MATH_TWO(atan2)
 
-static KrkValue _math_frexp(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _math_frexp(int argc, const KrkValue argv[], int hasKw) {
 	ONE_ARGUMENT(frexp)
-	FORCE_FLOAT(argv[0])
-	if (!IS_FLOATING(argv[0])) {
-		REAL_NUMBER_NOT(frexp,argv[0])
+	FORCE_FLOAT(argv[0],arg_0)
+	if (!IS_FLOATING(arg_0)) {
+		REAL_NUMBER_NOT(frexp,arg_0)
 	}
 	int exp = 0;
-	double result = frexp(AS_FLOATING(argv[0]), &exp);
+	double result = frexp(AS_FLOATING(arg_0), &exp);
 	KrkTuple * outValue = krk_newTuple(2);
 	outValue->values.values[0] = FLOATING_VAL(result);
 	outValue->values.values[1] = INTEGER_VAL(exp);
@@ -124,7 +125,7 @@ static KrkValue _math_frexp(int argc, KrkValue argv[], int hasKw) {
 }
 
 #define MATH_IS(func) \
-static KrkValue _math_ ## func(int argc, KrkValue argv[], int hasKw) { \
+static KrkValue _math_ ## func(int argc, const KrkValue argv[], int hasKw) { \
 	ONE_ARGUMENT(func) \
 	if (!IS_FLOATING(argv[0])) REAL_NUMBER_NOT(func,argv[0]) \
 	return BOOLEAN_VAL(func(AS_FLOATING(argv[0]))); \
diff --git a/src/obj_base.c b/src/obj_base.c
index ccb5ab6..fd15fcf 100644
--- a/src/obj_base.c
+++ b/src/obj_base.c
@@ -4,37 +4,37 @@
 #include <kuroko/memory.h>
 #include <kuroko/util.h>
 
-static KrkValue _type_init(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _type_init(int argc, const KrkValue argv[], int hasKw) {
 	if (argc != 2) return krk_runtimeError(vm.exceptions->argumentError, "type() takes 1 argument");
 	return OBJECT_VAL(krk_getType(argv[1]));
 }
 
 /* Class.__base__ */
-static KrkValue krk_baseOfClass(int argc, KrkValue argv[], int hasKw) {
+static KrkValue krk_baseOfClass(int argc, const KrkValue argv[], int hasKw) {
 	if (!IS_CLASS(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected class");
 	return AS_CLASS(argv[0])->base ? OBJECT_VAL(AS_CLASS(argv[0])->base) : NONE_VAL();
 }
 
 /* Class.__name */
-static KrkValue krk_nameOfClass(int argc, KrkValue argv[], int hasKw) {
+static KrkValue krk_nameOfClass(int argc, const KrkValue argv[], int hasKw) {
 	if (!IS_CLASS(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected class");
 	return AS_CLASS(argv[0])->name ? OBJECT_VAL(AS_CLASS(argv[0])->name) : NONE_VAL();
 }
 
 /* Class.__file__ */
-static KrkValue krk_fileOfClass(int argc, KrkValue argv[], int hasKw) {
+static KrkValue krk_fileOfClass(int argc, const KrkValue argv[], int hasKw) {
 	if (!IS_CLASS(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected class");
 	return AS_CLASS(argv[0])->filename ? OBJECT_VAL(AS_CLASS(argv[0])->filename) : NONE_VAL();
 }
 
 /* Class.__doc__ */
-static KrkValue krk_docOfClass(int argc, KrkValue argv[], int hasKw) {
+static KrkValue krk_docOfClass(int argc, const KrkValue argv[], int hasKw) {
 	if (!IS_CLASS(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected class");
 	return AS_CLASS(argv[0])->docstring ? OBJECT_VAL(AS_CLASS(argv[0])->docstring) : NONE_VAL();
 }
 
 /* Class.__str__() (and Class.__repr__) */
-static KrkValue _class_to_str(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _class_to_str(int argc, const KrkValue argv[], int hasKw) {
 	if (!IS_CLASS(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected class");
 
 	/* Determine if this class has a module */
@@ -59,7 +59,7 @@ static KrkValue _class_to_str(int argc, KrkValue argv[], int hasKw) {
 	return OBJECT_VAL(out);
 }
 
-static KrkValue _class_subclasses(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _class_subclasses(int argc, const KrkValue argv[], int hasKw) {
 	if (!IS_CLASS(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected class");
 
 	KrkClass * _class = AS_CLASS(argv[0]);
diff --git a/src/obj_dict.c b/src/obj_dict.c
index 55d9349..cbf6853 100644
--- a/src/obj_dict.c
+++ b/src/obj_dict.c
@@ -15,7 +15,7 @@
  * Exposed method called to produce dictionaries from `{expr: expr, ...}` sequences in managed code.
  * Presented in the global namespace as `dictOf(...)`. Expects arguments as `key,value,key,value`...
  */
-KrkValue krk_dict_of(int argc, KrkValue argv[], int hasKw) {
+KrkValue krk_dict_of(int argc, const KrkValue argv[], int hasKw) {
 	if (argc % 2 != 0) return krk_runtimeError(vm.exceptions->argumentError, "Expected even number of arguments to dictOf");
 	KrkInstance * outDict = krk_newInstance(vm.baseClasses->dictClass);
 	krk_push(OBJECT_VAL(outDict));
diff --git a/src/obj_list.c b/src/obj_list.c
index 9f83c21..4d6b3dd 100644
--- a/src/obj_list.c
+++ b/src/obj_list.c
@@ -28,7 +28,7 @@ static void _list_gcsweep(KrkInstance * self) {
  * Exposed method called to produce lists from [expr,...] sequences in managed code.
  * Presented in the global namespace as listOf(...)
  */
-KrkValue krk_list_of(int argc, KrkValue argv[], int hasKw) {
+KrkValue krk_list_of(int argc, const KrkValue argv[], int hasKw) {
 	KrkValue outList = OBJECT_VAL(krk_newInstance(vm.baseClasses->listClass));
 	krk_push(outList);
 	krk_initValueArray(AS_LIST(outList));
@@ -173,10 +173,11 @@ KRK_METHOD(list,extend,{
 	METHOD_TAKES_EXACTLY(1);
 	pthread_rwlock_wrlock(&self->rwlock);
 	KrkValueArray *  positionals = AS_LIST(argv[0]);
-	if (krk_valuesSame(argv[0],argv[1])) {
-		argv[1] = krk_list_of(self->values.count, self->values.values, 0);
+	KrkValue other = argv[1];
+	if (krk_valuesSame(argv[0],other)) {
+		other = krk_list_of(self->values.count, self->values.values, 0);
 	}
-	unpackIterableFast(argv[1]);
+	unpackIterableFast(other);
 _break_loop:
 	pthread_rwlock_unlock(&self->rwlock);
 })
@@ -488,7 +489,7 @@ KRK_METHOD(listiterator,__call__,{
 	}
 })
 
-static KrkValue _sorted(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _sorted(int argc, const KrkValue argv[], int hasKw) {
 	if (argc != 1) return krk_runtimeError(vm.exceptions->argumentError,"%s() takes %s %d argument%s (%d given)","sorted","exactly",1,"",argc);
 	KrkValue listOut = krk_list_of(0,NULL,0);
 	krk_push(listOut);
@@ -499,7 +500,7 @@ static KrkValue _sorted(int argc, KrkValue argv[], int hasKw) {
 	return krk_pop();
 }
 
-static KrkValue _reversed(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _reversed(int argc, const KrkValue argv[], int hasKw) {
 	/* FIXME The Python reversed() function produces an iterator and only works for things with indexing or a __reversed__ method;
 	 *       Building a list and reversing it like we do here is not correct! */
 	if (argc != 1) return krk_runtimeError(vm.exceptions->argumentError,"%s() takes %s %d argument%s (%d given)","reversed","exactly",1,"",argc);
diff --git a/src/obj_set.c b/src/obj_set.c
index 6512b37..40f46c2 100644
--- a/src/obj_set.c
+++ b/src/obj_set.c
@@ -221,7 +221,7 @@ KRK_METHOD(setiterator,__call__,{
 	} while (1);
 })
 
-KrkValue krk_set_of(int argc, KrkValue argv[], int hasKw) {
+KrkValue krk_set_of(int argc, const KrkValue argv[], int hasKw) {
 	KrkValue outSet = OBJECT_VAL(krk_newInstance(set));
 	krk_push(outSet);
 	krk_initTable(&AS_set(outSet)->entries);
diff --git a/src/obj_slice.c b/src/obj_slice.c
index 4984ef6..904f359 100644
--- a/src/obj_slice.c
+++ b/src/obj_slice.c
@@ -11,7 +11,7 @@ static void _slice_gcscan(KrkInstance * self) {
 	krk_markValue(((struct KrkSlice*)self)->step);
 }
 
-KrkValue krk_slice_of(int argc, KrkValue argv[], int hasKw) {
+KrkValue krk_slice_of(int argc, const KrkValue argv[], int hasKw) {
 	KrkValue outSlice = OBJECT_VAL(krk_newInstance(vm.baseClasses->sliceClass));
 	krk_push(outSlice);
 
diff --git a/src/obj_str.c b/src/obj_str.c
index 373a998..cda65ba 100644
--- a/src/obj_str.c
+++ b/src/obj_str.c
@@ -4,7 +4,7 @@
 #include <kuroko/memory.h>
 #include <kuroko/util.h>
 
-static KrkValue FUNC_NAME(striterator,__init__)(int,KrkValue[],int);
+static KrkValue FUNC_NAME(striterator,__init__)(int,const KrkValue[],int);
 
 #define CURRENT_CTYPE KrkString *
 #define CURRENT_NAME  self
@@ -410,7 +410,7 @@ static int charIn(char c, const char * str) {
  * Implements all three of strip, lstrip, rstrip.
  * Set which = 0, 1, 2 respectively
  */
-static KrkValue _string_strip_shared(int argc, KrkValue argv[], int which) {
+static KrkValue _string_strip_shared(int argc, const KrkValue argv[], int which) {
 	if (argc > 1 && IS_STRING(argv[1]) && AS_STRING(argv[1])->type != KRK_STRING_ASCII) {
 		return krk_runtimeError(vm.exceptions->notImplementedError, "str.strip() not implemented for Unicode strip lists");
 	}
diff --git a/src/obj_tuple.c b/src/obj_tuple.c
index aa10b9e..cc7c3a7 100644
--- a/src/obj_tuple.c
+++ b/src/obj_tuple.c
@@ -9,7 +9,7 @@
 	if (index < 0) index += self->values.count; \
 	if (index < 0 || index >= (krk_integer_type)self->values.count) return krk_runtimeError(vm.exceptions->indexError, "tuple index out of range: " PRIkrk_int, index)
 
-static KrkValue _tuple_init(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _tuple_init(int argc, const KrkValue argv[], int hasKw) {
 	if (argc == 1) {
 		return OBJECT_VAL(krk_newTuple(0));
 	} else if (argc == 2) {
@@ -30,7 +30,7 @@ static KrkValue _tuple_init(int argc, KrkValue argv[], int hasKw) {
 }
 
 /* tuple creator */
-KrkValue krk_tuple_of(int argc, KrkValue argv[], int hasKw) {
+KrkValue krk_tuple_of(int argc, const KrkValue argv[], int hasKw) {
 	KrkTuple * self = krk_newTuple(argc);
 	krk_push(OBJECT_VAL(self));
 	for (size_t i = 0; i < (size_t)argc; ++i) {
@@ -150,7 +150,7 @@ struct TupleIter {
 	int i;
 };
 
-static KrkValue _tuple_iter_init(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _tuple_iter_init(int argc, const KrkValue argv[], int hasKw) {
 	struct TupleIter * self = (struct TupleIter *)AS_OBJECT(argv[0]);
 	self->myTuple = argv[1];
 	self->i = 0;
@@ -161,7 +161,7 @@ static void _tuple_iter_gcscan(KrkInstance * self) {
 	krk_markValue(((struct TupleIter*)self)->myTuple);
 }
 
-static KrkValue _tuple_iter_call(int argc, KrkValue argv[], int hasKw) {
+static KrkValue _tuple_iter_call(int argc, const KrkValue argv[], int hasKw) {
 	struct TupleIter * self = (struct TupleIter *)AS_OBJECT(argv[0]);
 	KrkValue t = self->myTuple; /* Tuple to iterate */
 	int i = self->i;
diff --git a/src/os.c b/src/os.c
index c1f280d..a9c3874 100644
--- a/src/os.c
+++ b/src/os.c
@@ -465,7 +465,7 @@ KRK_FUNC(get_terminal_size,{
 })
 #endif
 
-static int makeArgs(int count, KrkValue * values, char *** argsOut, const char * _method_name) {
+static int makeArgs(int count, const KrkValue * values, char *** argsOut, const char * _method_name) {
 	char ** out = malloc(sizeof(char*)*(count+1));
 	for (int i = 0; i < count; ++i) {
 		if (!IS_STRING(values[i])) {
diff --git a/src/vm.c b/src/vm.c
index e1b0c79..03cb580 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -790,7 +790,7 @@ _errorAfterKeywords:
  * If the stack is reallocated within this call, the old stack will not be freed until
  * all such nested calls through krk_callNativeOnStack have returned.
  */
-KrkValue krk_callNativeOnStack(NativeFn native, size_t argCount, KrkValue *stackArgs, int hasKw) {
+KrkValue krk_callNativeOnStack(NativeFn native, size_t argCount, const KrkValue *stackArgs, int hasKw) {
 
 	/**
 	 * If someone is already preserving this stack, we can just call directly.