diff --git a/src/type.zig b/src/type.zig
index 5ff9da8913..339485c137 100644
--- a/src/type.zig
+++ b/src/type.zig
@@ -6593,6 +6593,8 @@ pub const CType = enum {
                         .powerpcle,
                         .powerpc64,
                         .powerpc64le,
+                        .wasm32,
+                        .wasm64,
                         => return 128,
 
                         else => return 64,
@@ -6641,6 +6643,8 @@ pub const CType = enum {
                         .powerpcle,
                         .powerpc64,
                         .powerpc64le,
+                        .wasm32,
+                        .wasm64,
                         => return 128,
 
                         else => return 64,
diff --git a/test/behavior/cast.zig b/test/behavior/cast.zig
index fa0877258c..4c6dab2dbb 100644
--- a/test/behavior/cast.zig
+++ b/test/behavior/cast.zig
@@ -1430,6 +1430,7 @@ test "coerce between pointers of compatible differently-named floats" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
 
     if (builtin.os.tag == .windows) {
         // https://github.com/ziglang/zig/issues/12396
diff --git a/test/c_abi/cfuncs.c b/test/c_abi/cfuncs.c
index f5c90adba0..391e87fc67 100644
--- a/test/c_abi/cfuncs.c
+++ b/test/c_abi/cfuncs.c
@@ -33,6 +33,7 @@ void zig_five_integers(int32_t, int32_t, int32_t, int32_t, int32_t);
 
 void zig_f32(float);
 void zig_f64(double);
+void zig_longdouble(long double);
 void zig_five_floats(float, float, float, float, float);
 
 bool zig_ret_bool();
@@ -157,6 +158,7 @@ void run_c_tests(void) {
 
     zig_f32(12.34f);
     zig_f64(56.78);
+    zig_longdouble(12.34l);
     zig_five_floats(1.0f, 2.0f, 3.0f, 4.0f, 5.0f);
 
     zig_ptr((void*)0xdeadbeefL);
@@ -271,6 +273,10 @@ void c_f64(double x) {
     assert_or_panic(x == 56.78);
 }
 
+void c_long_double(long double x) {
+    assert_or_panic(x == 12.34l);
+}
+
 void c_ptr(void *x) {
     assert_or_panic(x == (void*)0xdeadbeefL);
 }
diff --git a/test/c_abi/main.zig b/test/c_abi/main.zig
index 71a53bedea..145bbc384a 100644
--- a/test/c_abi/main.zig
+++ b/test/c_abi/main.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const builtin = @import("builtin");
 const print = std.debug.print;
 const expect = std.testing.expect;
 
@@ -89,6 +90,7 @@ export fn zig_struct_u128(a: U128) void {
 
 extern fn c_f32(f32) void;
 extern fn c_f64(f64) void;
+extern fn c_long_double(c_longdouble) void;
 
 // On windows x64, the first 4 are passed via registers, others on the stack.
 extern fn c_five_floats(f32, f32, f32, f32, f32) void;
@@ -107,12 +109,21 @@ test "C ABI floats" {
     c_five_floats(1.0, 2.0, 3.0, 4.0, 5.0);
 }
 
+test "C ABI long double" {
+    if (!builtin.cpu.arch.isWasm()) return error.SkipZigTest;
+    c_long_double(12.34);
+}
+
 export fn zig_f32(x: f32) void {
     expect(x == 12.34) catch @panic("test failure: zig_f32");
 }
 export fn zig_f64(x: f64) void {
     expect(x == 56.78) catch @panic("test failure: zig_f64");
 }
+export fn zig_longdouble(x: c_longdouble) void {
+    if (!builtin.cpu.arch.isWasm()) return; // waiting for #1481
+    expect(x == 12.34) catch @panic("test failure: zig_longdouble");
+}
 
 extern fn c_ptr(*anyopaque) void;