diff --git a/library/compiler/compiler-macros.factor b/library/compiler/compiler-macros.factor
index f210a5ba80..b5c9d50894 100644
--- a/library/compiler/compiler-macros.factor
+++ b/library/compiler/compiler-macros.factor
@@ -28,48 +28,32 @@
 IN: compiler
 USE: alien
 
-: DATASTACK ( -- ptr )
-    #! A pointer to a pointer to the datastack top.
-    "ds" dlsym-self ;
-
-: CALLSTACK ( -- ptr )
-    #! A pointer to a pointer to the callstack top.
-    "cs" dlsym-self ;
-
 : LITERAL ( cell -- )
     #! Push literal on data stack.
-    #! Assume that it is ok to clobber EAX without saving.
-    DATASTACK EAX [I]>R
-    EAX I>[R]
-    4 DATASTACK I+[I] ;
+    ESI I>[R]
+    4 ESI R+I ;
 
 : [LITERAL] ( cell -- )
     #! Push complex literal on data stack by following an
     #! indirect pointer.
-    ECX PUSH-R
-    ( cell -- ) ECX [I]>R
-    DATASTACK EAX [I]>R
-    ECX EAX R>[R]
-    4 DATASTACK I+[I]
-    ECX POP-R ;
+    EAX [I]>R
+    EAX ESI R>[R]
+    4 ESI R+I ;
 
 : PUSH-DS ( -- )
     #! Push contents of EAX onto datastack.
-    ECX PUSH-R
-    DATASTACK ECX [I]>R
-    EAX ECX R>[R]
-    4 DATASTACK I+[I]
-    ECX POP-R ;
+    EAX ESI R>[R]
+    4 ESI R+I ;
 
 : PEEK-DS ( -- )
     #! Peek datastack, store pointer to datastack top in EAX.
-    DATASTACK EAX [I]>R
+    ESI EAX R>R
     4 EAX R-I ;
 
 : POP-DS ( -- )
     #! Pop datastack, store pointer to datastack top in EAX.
     PEEK-DS
-    EAX DATASTACK R>[I] ;
+    EAX ESI R>R ;
 
 : SELF-CALL ( name -- )
     #! Call named C function in Factor interpreter executable.
diff --git a/native/error.c b/native/error.c
index 84932d7b7c..350c6e2dfc 100644
--- a/native/error.c
+++ b/native/error.c
@@ -1,5 +1,10 @@
 #include "factor.h"
 
+void init_errors(void)
+{
+	thrown_error = F;
+}
+
 void fatal_error(char* msg, CELL tagged)
 {
 	fprintf(stderr,"Fatal error: %s %ld\n",msg,tagged);
@@ -15,9 +20,9 @@ void critical_error(char* msg, CELL tagged)
 
 void throw_error(CELL error)
 {
-	dpush(error);
-	/* Execute the 'throw' word */
-	call(userenv[BREAK_ENV]);
+	/* dpush(error); */
+	/* call(userenv[BREAK_ENV]); */
+	thrown_error = error;
 
 	/* Return to run() method */
 	siglongjmp(toplevel,1);
diff --git a/native/error.h b/native/error.h
index 2b6dda1b5a..47d1a98170 100644
--- a/native/error.h
+++ b/native/error.h
@@ -19,6 +19,11 @@
 #define ERROR_CALLSTACK_OVERFLOW (18<<3)
 #define ERROR_CLOSED (19<<3)
 
+/* When throw_error throws an error, it sets this global and
+longjmps back to the top-level. */
+CELL thrown_error;
+
+void init_errors(void);
 void fatal_error(char* msg, CELL tagged);
 void critical_error(char* msg, CELL tagged);
 void throw_error(CELL object);
diff --git a/native/factor.c b/native/factor.c
index ad200c062b..67f2ff9bd0 100644
--- a/native/factor.c
+++ b/native/factor.c
@@ -18,6 +18,7 @@ int main(int argc, char** argv)
 	init_io();
 	init_signals();
 	init_compiler();
+	init_errors();
 
 	args = F;
 	while(--argc != 0)
@@ -27,7 +28,7 @@ int main(int argc, char** argv)
 
 	userenv[ARGS_ENV] = args;
 
-#if defined(i386) || defined(__i386) || defined(__i386__)
+#ifdef FACTOR_X86
 	userenv[CPU_ENV] = tag_object(from_c_string("x86"));
 #else
 	userenv[CPU_ENV] = tag_object(from_c_string("unknown"));
diff --git a/native/factor.h b/native/factor.h
index d5d310ab81..2b29cf9d5b 100644
--- a/native/factor.h
+++ b/native/factor.h
@@ -27,6 +27,10 @@
 #include <dlfcn.h>
 #endif /* FFI */
 
+#if defined(i386) || defined(__i386) || defined(__i386__)
+    #define FACTOR_X86
+#endif
+
 #define INLINE inline static
 
 /* CELL must be 32 bits and your system must have 32-bit pointers */
diff --git a/native/run.c b/native/run.c
index 93e2a07b0e..136ce257d3 100644
--- a/native/run.c
+++ b/native/run.c
@@ -16,6 +16,13 @@ void run(void)
 
 	/* Error handling. */
 	sigsetjmp(toplevel, 1);
+	if(thrown_error != F)
+	{
+		dpush(thrown_error);
+		/* Notify any 'catch' blocks */
+		call(userenv[BREAK_ENV]);
+		thrown_error = F;
+	}
 
 	for(;;)
 	{
diff --git a/native/run.h b/native/run.h
index 9e658ac5f9..4323d0a1ef 100644
--- a/native/run.h
+++ b/native/run.h
@@ -25,9 +25,7 @@ CELL callframe;
 CELL ds_bot;
 
 /* raw pointer to datastack top */
-/* #define X86_STACK */
-
-#ifdef X86_STACK
+#ifdef FACTOR_X86
 register CELL ds asm("%esi");
 #else
 CELL ds;
@@ -37,11 +35,7 @@ CELL ds;
 CELL cs_bot;
 
 /* raw pointer to callstack top */
-#ifdef X86_STACK
-register CELL cs asm("edi");
-#else
 CELL cs;
-#endif
 
 /* raw pointer to currently executing word */
 WORD* executing;