diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 09612c8d..b779aed 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -5262,7 +5262,7 @@
         // Branch cases into compressed and uncompressed for each index's type.
         uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
         NearLabel done, not_compressed;
-        __ testl(Address(obj, count_offset), Immediate(1));
+        __ testb(Address(obj, count_offset), Immediate(1));
         codegen_->MaybeRecordImplicitNullCheck(instruction);
         static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
                       "Expecting 0=compressed, 1=uncompressed");
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 0879992..179bf6d 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -4720,7 +4720,7 @@
         // Branch cases into compressed and uncompressed for each index's type.
         uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
         NearLabel done, not_compressed;
-        __ testl(Address(obj, count_offset), Immediate(1));
+        __ testb(Address(obj, count_offset), Immediate(1));
         codegen_->MaybeRecordImplicitNullCheck(instruction);
         static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
                       "Expecting 0=compressed, 1=uncompressed");
diff --git a/disassembler/disassembler_x86.cc b/disassembler/disassembler_x86.cc
index ff05733..a289433 100644
--- a/disassembler/disassembler_x86.cc
+++ b/disassembler/disassembler_x86.cc
@@ -1306,7 +1306,7 @@
     has_modrm = true;
     reg_is_opcode = true;
     store = true;
-    immediate_bytes = ((instr[1] & 0x38) == 0) ? 1 : 0;
+    immediate_bytes = ((instr[1] & 0x38) == 0) ? (instr[0] == 0xF7 ? 4 : 1) : 0;
     break;
   case 0xFF:
     {