--- a/js/src/jit/x86/Assembler-x86.h
+++ b/js/src/jit/x86/Assembler-x86.h
@@ -129,17 +129,17 @@ static constexpr Register RegExpMatcherL
 
 // Registerd used in RegExpTester instruction (do not use ReturnReg).
 static constexpr Register RegExpTesterRegExpReg = CallTempReg0;
 static constexpr Register RegExpTesterStringReg = CallTempReg2;
 static constexpr Register RegExpTesterLastIndexReg = CallTempReg3;
 
 // GCC stack is aligned on 16 bytes. Ion does not maintain this for internal
 // calls. wasm code does.
-#if defined(__GNUC__)
+#if defined(__GNUC__) && !defined(__MINGW32__)
 static constexpr uint32_t ABIStackAlignment = 16;
 #else
 static constexpr uint32_t ABIStackAlignment = 4;
 #endif
 static constexpr uint32_t CodeAlignment = 16;
 static constexpr uint32_t JitStackAlignment = 16;
 
 static constexpr uint32_t JitStackValueAlignment = JitStackAlignment / sizeof(Value);