diff --git a/moo/kernel/FFI.moo b/moo/kernel/FFI.moo
index 62705a5..90bbeb0 100644
--- a/moo/kernel/FFI.moo
+++ b/moo/kernel/FFI.moo
@@ -35,7 +35,7 @@ class FFI(Object)
 
 		x := self.ffi open(name).
 		//(x isError) ifTrue: [^x].
-		if (x isError) { FFIException signal: ('Unable to open %s' strfmt(name)) }.
+		if (x isError) { FFIException signal: ('Unable to open %O' strfmt(name)) }.
 
 		^self.
 	}
@@ -51,7 +51,7 @@ class FFI(Object)
 
 		/* f := self.funcs at: name ifAbsent: [ 
 			f := self.ffi getsym(name).
-			if (f isError) { FFIException signal: ('Unable to find %s' strfmt(name)) }.
+			if (f isError) { FFIException signal: ('Unable to find %O' strfmt(name)) }.
 			self.funcs at: name put: f.
 			f. // need this as at:put: returns an association
 		]. */
@@ -60,12 +60,12 @@ class FFI(Object)
 		if (f isNil)
 		{
 			f := self.ffi getsym(name).
-			if (f isError) { FFIException signal: ('Unable to find %s' strfmt(name)) }.
+			if (f isError) { FFIException signal: ('Unable to find %O' strfmt(name)) }.
 			self.funcs at: name put: f.
 		}.
 
 		rc := self.ffi call(f, sig, args).
-		if (rc isError)	{ FFIException signal: ('Unable to call %s' strfmt(name)) }.
+		if (rc isError)	{ FFIException signal: ('Unable to call %O' strfmt(name)) }.
 
 		^rc.
 	}
diff --git a/moo/mod/ffi.c b/moo/mod/ffi.c
index 81d26a0..38ccf57 100644
--- a/moo/mod/ffi.c
+++ b/moo/mod/ffi.c
@@ -390,14 +390,14 @@ static MOO_INLINE int add_ffi_arg (moo_t* moo, ffi_t* ffi, moo_ooch_t fmtc, int
 			break;
 
 		case FMTC_LONGLONG:
-		#if (MOO_SIZEOF_LONG_LONG <= 0)
+		#if (MOO_SIZEOF_LONG_LONG <= MOO_SIZEOF_LONG)
 			goto arg_as_long;
 		#else
 			if (_unsigned)
 			{
-				moo_oow_t v;
+				moo_uintmax_t v;
 				/* TODO: if (MOO_SIZEOF_LONG_LONG > MOO_SIZEOF_OOI_T) use moo_inttointmax() or something */
-				if (moo_inttooow(moo, arg, &v) == 0) goto oops;
+				if (moo_inttouintmax(moo, arg, &v) == 0) goto oops;
 			#if defined(USE_DYNCALL)
 				dcArgLongLong (ffi->dc, v);
 			#elif defined(USE_LIBFFI)
@@ -407,8 +407,8 @@ static MOO_INLINE int add_ffi_arg (moo_t* moo, ffi_t* ffi, moo_ooch_t fmtc, int
 			}
 			else
 			{
-				moo_ooi_t v;
-				if (moo_inttoooi(moo, arg, &v) == 0) goto oops;
+				moo_intmax_t v;
+				if (moo_inttointmax(moo, arg, &v) == 0) goto oops;
 			#if defined(USE_DYNCALL)
 				dcArgLongLong (ffi->dc, v);
 			#elif defined(USE_LIBFFI)
@@ -671,7 +671,7 @@ static moo_pfrc_t pf_call (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 
 		case FMTC_LONGLONG:
 		{
-		#if (MOO_SIZEOF_LONG_LONG <= 0)
+		#if (MOO_SIZEOF_LONG_LONG <= MOO_SIZEOF_LONG)
 			goto ret_as_long;
 		#else
 			moo_oop_t r;