diff --git a/examples/sysir/run_samples.bat b/examples/sysir/run_samples.bat
new file mode 100644
index 00000000..d75243a5
--- /dev/null
+++ b/examples/sysir/run_samples.bat
@@ -0,0 +1,4 @@
+janet.exe examples/sysir/samples.janet > temp.nasm
+nasm -fwin64 temp.nasm -l temp.lst -o temp.o
+link temp.o legacy_stdio_definitions.lib msvcrt.lib /out:temp.exe
+temp.exe
diff --git a/examples/sysir/samples.janet b/examples/sysir/samples.janet
index 819d5fc9..8a495d00 100644
--- a/examples/sysir/samples.janet
+++ b/examples/sysir/samples.janet
@@ -32,8 +32,8 @@
      (return x)))
 
 (def main-fn
-  '(defn _start:void []
-     (syscall 1 1 "Hello, world!\n" 14)
+  '(defn WinMain:void []
+     #(syscall 1 1 "Hello, world!\n" 14)
      (doloop 10 20)
      (exit (the int 0))
      (return)))
diff --git a/src/core/sysir.c b/src/core/sysir.c
index f0a08791..0ba5b667 100644
--- a/src/core/sysir.c
+++ b/src/core/sysir.c
@@ -287,7 +287,7 @@ static uint32_t instr_read_type_operand(Janet x, JanetSysIR *ir, ReadOpMode rmod
             return (uint32_t) n;
         } else if (rmode == READ_TYPE_FORWARD_REF) {
             uint32_t operand = linkage->type_def_count++;
-            janet_table_put(linkage->type_name_lookup, x, janet_wrap_number(-operand - 1));
+            janet_table_put(linkage->type_name_lookup, x, janet_wrap_number(-(int64_t)operand - 1));
             return operand;
         } else if (rmode == READ_TYPE_DEFINITION) {
             uint32_t operand = linkage->type_def_count++;
@@ -1600,7 +1600,7 @@ void janet_sys_ir_lower_to_ir(JanetSysIRLinkage *linkage, JanetArray *into) {
                     build_tuple[0] = janet_csymbolv("type-array");
                     build_tuple[1] = janet_sys_get_desttype(linkage, instruction.array.dest_type);
                     build_tuple[2] = janet_sys_get_desttype(linkage, instruction.array.type);
-                    build_tuple[4] = janet_wrap_number(instruction.array.fixed_count);
+                    build_tuple[4] = janet_wrap_number((double) instruction.array.fixed_count);
                     break;
             }
             const Janet *tuple = janet_tuple_end(build_tuple);
diff --git a/src/core/sysir_x86.c b/src/core/sysir_x86.c
index bcbdb680..f70c5756 100644
--- a/src/core/sysir_x86.c
+++ b/src/core/sysir_x86.c
@@ -585,8 +585,8 @@ void janet_sys_ir_lower_to_x64(JanetSysIRLinkage *linkage, JanetBuffer *buffer)
                     sysemit_operand(&ctx, instruction.branch.cond, ", 0\n");
                     janet_formatb(buffer,
                                   "%s label_%d_%u\n",
-                                  instruction.opcode == JANET_SYSOP_BRANCH ? "jnz " : "jz ",
-                                  i, instruction.branch.to);
+                                  instruction.opcode == JANET_SYSOP_BRANCH ? "jnz" : "jz",
+                                  i, (uint64_t) instruction.branch.to);
                     break;
                 case JANET_SYSOP_JUMP:
                     janet_formatb(buffer, "jmp label_%d_%u\n", i, instruction.jump.to);