diff --git a/src/Compilation.zig b/src/Compilation.zig
index 64548a96..8c2f16ef 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -751,6 +751,10 @@ fn generateExactWidthType(comp: *const Compilation, w: anytype, mapper: StringIn
     try comp.generateSuffixMacro(prefix.constSlice(), w, ty);
 }
 
+pub fn hasFloat128(comp: *const Compilation) bool {
+    return target_util.hasFloat128(comp.target);
+}
+
 pub fn hasHalfPrecisionFloatABI(comp: *const Compilation) bool {
     return comp.langopts.allow_half_args_and_returns or target_util.hasHalfPrecisionFloatABI(comp.target);
 }
diff --git a/src/Parser.zig b/src/Parser.zig
index 16748b4e..422c655c 100644
--- a/src/Parser.zig
+++ b/src/Parser.zig
@@ -1852,7 +1852,12 @@ fn typeSpec(p: *Parser, ty: *Type.Builder) Error!bool {
             .keyword_double => try ty.combine(p, .double, p.tok_i),
             .keyword_complex => try ty.combine(p, .complex, p.tok_i),
             .keyword_float80 => try ty.combine(p, .float80, p.tok_i),
-            .keyword_float128 => try ty.combine(p, .float128, p.tok_i),
+            .keyword_float128_1, .keyword_float128_2 => {
+                if (!p.comp.hasFloat128()) {
+                    try p.errStr(.type_not_supported_on_target, p.tok_i, p.tok_ids[p.tok_i].lexeme().?);
+                }
+                try ty.combine(p, .float128, p.tok_i);
+            },
             .keyword_atomic => {
                 const atomic_tok = p.tok_i;
                 p.tok_i += 1;
diff --git a/src/Tokenizer.zig b/src/Tokenizer.zig
index d6bd7079..e20f76d9 100644
--- a/src/Tokenizer.zig
+++ b/src/Tokenizer.zig
@@ -259,7 +259,10 @@ pub const Token = struct {
         keyword_asm1,
         keyword_asm2,
         keyword_float80,
-        keyword_float128,
+        /// _Float128
+        keyword_float128_1,
+        /// __float128
+        keyword_float128_2,
         keyword_int128,
         keyword_imag1,
         keyword_imag2,
@@ -415,7 +418,8 @@ pub const Token = struct {
                 .keyword_asm1,
                 .keyword_asm2,
                 .keyword_float80,
-                .keyword_float128,
+                .keyword_float128_1,
+                .keyword_float128_2,
                 .keyword_int128,
                 .keyword_imag1,
                 .keyword_imag2,
@@ -698,7 +702,8 @@ pub const Token = struct {
                 .keyword_asm1 => "__asm",
                 .keyword_asm2 => "__asm__",
                 .keyword_float80 => "__float80",
-                .keyword_float128 => "__float18",
+                .keyword_float128_1 => "_Float128",
+                .keyword_float128_2 => "__float128",
                 .keyword_int128 => "__int128",
                 .keyword_imag1 => "__imag",
                 .keyword_imag2 => "__imag__",
@@ -974,7 +979,8 @@ pub const Token = struct {
         .{ "__asm", .keyword_asm1 },
         .{ "__asm__", .keyword_asm2 },
         .{ "__float80", .keyword_float80 },
-        .{ "__float128", .keyword_float128 },
+        .{ "_Float128", .keyword_float128_1 },
+        .{ "__float128", .keyword_float128_2 },
         .{ "__int128", .keyword_int128 },
         .{ "__imag", .keyword_imag1 },
         .{ "__imag__", .keyword_imag2 },
diff --git a/src/target.zig b/src/target.zig
index 526fce33..7bc22f4a 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -258,6 +258,21 @@ pub fn systemCompiler(target: std.Target) LangOpts.Compiler {
     return .clang;
 }
 
+pub fn hasFloat128(target: std.Target) bool {
+    if (target.cpu.arch.isWasm()) return true;
+    if (target.isDarwin()) return false;
+    if (target.cpu.arch.isPPC() or target.cpu.arch.isPPC64()) return std.Target.powerpc.featureSetHas(target.cpu.features, .float128);
+    return switch (target.os.tag) {
+        .dragonfly,
+        .haiku,
+        .linux,
+        .openbsd,
+        .solaris,
+        => target.cpu.arch.isX86(),
+        else => false,
+    };
+}
+
 pub fn hasInt128(target: std.Target) bool {
     if (target.cpu.arch == .wasm32) return true;
     if (target.cpu.arch == .x86_64) return true;
diff --git a/test/cases/darwin __float128.c b/test/cases/darwin __float128.c
new file mode 100644
index 00000000..41f8b622
--- /dev/null
+++ b/test/cases/darwin __float128.c	
@@ -0,0 +1,5 @@
+//aro-args --target=x86_64-macos
+__float128 q = 0.0;
+
+#define EXPECTED_ERRORS "darwin __float128.c:2:1: error: __float128 is not supported on this target" \
+
diff --git a/test/cases/linux __float128.c b/test/cases/linux __float128.c
new file mode 100644
index 00000000..1859b454
--- /dev/null
+++ b/test/cases/linux __float128.c	
@@ -0,0 +1,10 @@
+//aro-args --target=x86_64-linux-gnu
+void foo(void) {
+    __float128 q = 0.0;
+    _Float128 q2 = 0.0;
+
+    // q = 1.0q;
+    // q = 1.0f128;
+}
+
+#define TESTS_SKIPPED 2