diff -r 5e61d64d83a9 src/vm/jit/x86_64/codegen.c
--- a/src/vm/jit/x86_64/codegen.c	Mon Jun 09 17:34:41 2008 +0200
+++ b/src/vm/jit/x86_64/codegen.c	Wed Jun 11 23:33:37 2008 +0200
@@ -50,6 +50,7 @@
 #include "vm/builtin.h"
 #include "vm/exceptions.h"
 #include "vm/global.h"
+#include "vm/primitive.h"
 #include "vm/stringlocal.h"
 #include "vm/vm.h"
 
@@ -3054,6 +3055,20 @@
 	case TYPE_INT:
 	case TYPE_LNG:
 	case TYPE_ADR:
+		switch (md->returntype.decltype) {
+		case PRIMITIVETYPE_BOOLEAN:
+			M_BZEXT(REG_RESULT, REG_RESULT);
+			break;
+		case PRIMITIVETYPE_BYTE:
+			M_BSEXT(REG_RESULT, REG_RESULT);
+			break;
+		case PRIMITIVETYPE_CHAR:
+			M_CZEXT(REG_RESULT, REG_RESULT);
+			break;
+		case PRIMITIVETYPE_SHORT:
+			M_SSEXT(REG_RESULT, REG_RESULT);
+			break;
+		}
 		M_LST(REG_RESULT, REG_SP, 0 * 8);
 		break;
 	case TYPE_FLT:
diff -r 5e61d64d83a9 src/vm/jit/x86_64/codegen.h
--- a/src/vm/jit/x86_64/codegen.h	Mon Jun 09 17:34:41 2008 +0200
+++ b/src/vm/jit/x86_64/codegen.h	Wed Jun 11 23:33:37 2008 +0200
@@ -256,6 +256,7 @@
 #define M_SSEXT(a,b)            emit_movswq_reg_reg(cd, (a), (b))
 #define M_ISEXT(a,b)            emit_movslq_reg_reg(cd, (a), (b))
 
+#define M_BZEXT(a,b)            emit_movzbq_reg_reg(cd, (a), (b))
 #define M_CZEXT(a,b)            emit_movzwq_reg_reg(cd, (a), (b))
 
 #define M_ISLL_IMM(a,b)         emit_shiftl_imm_reg(cd, SHIFT_SHL, (a), (b))
diff -r 5e61d64d83a9 src/vm/jit/x86_64/emit.c
--- a/src/vm/jit/x86_64/emit.c	Mon Jun 09 17:34:41 2008 +0200
+++ b/src/vm/jit/x86_64/emit.c	Wed Jun 11 23:33:37 2008 +0200
@@ -1179,6 +1179,16 @@
 }
 
 
+void emit_movzbq_reg_reg(codegendata *cd, s8 reg, s8 dreg)
+{
+	emit_rex(1,(dreg),0,(reg));
+	*(cd->mcodeptr++) = 0x0f;
+	*(cd->mcodeptr++) = 0xb6;
+	/* XXX: why do reg and dreg have to be exchanged */
+	emit_reg((dreg),(reg));
+}
+
+
 void emit_movzwq_reg_reg(codegendata *cd, s8 reg, s8 dreg)
 {
 	emit_rex(1,(dreg),0,(reg));
diff -r 5e61d64d83a9 src/vm/jit/x86_64/emit.h
--- a/src/vm/jit/x86_64/emit.h	Mon Jun 09 17:34:41 2008 +0200
+++ b/src/vm/jit/x86_64/emit.h	Wed Jun 11 23:33:37 2008 +0200
@@ -219,6 +219,7 @@
 void emit_movswq_membase_reg(codegendata *cd, s8 basereg, s8 disp, s8 dreg);
 void emit_movslq_reg_reg(codegendata *cd, s8 reg, s8 dreg);
 void emit_movslq_membase_reg(codegendata *cd, s8 basereg, s8 disp, s8 dreg);
+void emit_movzbq_reg_reg(codegendata *cd, s8 reg, s8 dreg);
 void emit_movzwq_reg_reg(codegendata *cd, s8 reg, s8 dreg);
 void emit_movzwq_membase_reg(codegendata *cd, s8 basereg, s8 disp, s8 dreg);
 void emit_movswq_memindex_reg(codegendata *cd, s8 disp, s8 basereg, s8 indexreg, s8 scale, s8 reg);