diff --git a/basis/compiler/cfg/linear-scan/allocation/allocation-tests.factor b/basis/compiler/cfg/linear-scan/allocation/allocation-tests.factor
index 938c1de56a..08aaad1de6 100644
--- a/basis/compiler/cfg/linear-scan/allocation/allocation-tests.factor
+++ b/basis/compiler/cfg/linear-scan/allocation/allocation-tests.factor
@@ -39,7 +39,7 @@ cpu x86.64? [
         interval-[30,46] machine-registers register-status
     ] unit-test
 
-    { { RCX 1/0. } } [
+    { { RBX 1/0. } } [
         f machine-registers init-allocator
         interval-[30,60] add-active
         interval-[30,46] machine-registers register-status
@@ -49,9 +49,9 @@ cpu x86.64? [
     {
         {
             { RAX 1/0. }
+            { RBX 1/0. }
             { RCX 1/0. }
             { RDX 1/0. }
-            { RBX 1/0. }
             { RBP 1/0. }
             { RSI 1/0. }
             { RDI 1/0. }
diff --git a/basis/cpu/x86/64/64.factor b/basis/cpu/x86/64/64.factor
index 178cd4bfd7..eb50168eaa 100644
--- a/basis/cpu/x86/64/64.factor
+++ b/basis/cpu/x86/64/64.factor
@@ -32,7 +32,7 @@ M: x86.64 frame-reg RBP ;
 
 M: x86.64 machine-registers
     {
-        { int-regs { RAX RCX RDX RBX RBP RSI RDI R8 R9 R10 R11 R12 } }
+        { int-regs { RAX RBX RCX RDX RBP RSI RDI R8 R9 R10 R11 R12 } }
         { float-regs {
             XMM0 XMM1 XMM2 XMM3 XMM4 XMM5 XMM6 XMM7
             XMM8 XMM9 XMM10 XMM11 XMM12 XMM13 XMM14 XMM15