diff --git a/Source/Core/Common/x64ABI.h b/Source/Core/Common/x64ABI.h
index ee8e596756..66abeee5ef 100644
--- a/Source/Core/Common/x64ABI.h
+++ b/Source/Core/Common/x64ABI.h
@@ -30,10 +30,11 @@
 #define ABI_PARAM3 R8
 #define ABI_PARAM4 R9
 
+// xmm0-xmm15 use the upper 16 bits in the functions that push/pop registers.
 #define ABI_ALL_CALLER_SAVED ((1 << RAX) | (1 << RCX) | (1 << RDX) | (1 << R8) | \
                               (1 << R9) | (1 << R10) | (1 << R11) | \
-                              (1 << XMM0) | (1 << XMM1) | (1 << XMM2) | (1 << XMM3) | \
-                              (1 << XMM4) | (1 << XMM5))
+                              (1 << (XMM0+16)) | (1 << (XMM1+16)) | (1 << (XMM2+16)) | (1 << (XMM3+16)) | \
+                              (1 << (XMM4+16)) | (1 << (XMM5+16)))
 
 #else  //64-bit Unix / OS X
 
@@ -44,6 +45,8 @@
 #define ABI_PARAM5 R8
 #define ABI_PARAM6 R9
 
+// FIXME: avoid pushing all 16 XMM registers when possible? most functions we call probably
+// don't actually clobber them.
 #define ABI_ALL_CALLER_SAVED ((1 << RAX) | (1 << RCX) | (1 << RDX) | (1 << RDI) | \
                               (1 << RSI) | (1 << R8) | (1 << R9) | (1 << R10) | (1 << R11) | \
                               0xffff0000 /* xmm0..15 */)
diff --git a/Source/Core/Core/PowerPC/JitCommon/JitAsmCommon.cpp b/Source/Core/Core/PowerPC/JitCommon/JitAsmCommon.cpp
index 81327d36ea..3875acaa27 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitAsmCommon.cpp
+++ b/Source/Core/Core/PowerPC/JitCommon/JitAsmCommon.cpp
@@ -9,7 +9,7 @@
 #include "Core/PowerPC/JitCommon/JitBase.h"
 
 #define QUANTIZED_REGS_TO_SAVE (ABI_ALL_CALLER_SAVED & ~((1 << RAX) | (1 << RCX) | (1 << RDX) | \
-                                                         (1 << XMM0) | (1 << XMM1)))
+                                                         (1 << (XMM0+16)) | (1 << (XMM1+16))))
 
 using namespace Gen;