diff --git a/src/codegen/wasm.zig b/src/codegen/wasm.zig
index 827f6c366a..2d69dc6bba 100644
--- a/src/codegen/wasm.zig
+++ b/src/codegen/wasm.zig
@@ -225,6 +225,7 @@ pub const Context = struct {
             .ret => self.genRet(inst.castTag(.ret).?),
             .retvoid => WValue.none,
             .store => self.genStore(inst.castTag(.store).?),
+            .sub => self.genSub(inst.castTag(.sub).?),
             .unreach => self.genUnreachable(inst.castTag(.unreach).?),
             else => self.fail(inst.src, "TODO: Implement wasm inst: {s}", .{inst.tag}),
         };
@@ -324,6 +325,25 @@ pub const Context = struct {
         return .none;
     }
 
+    fn genSub(self: *Context, inst: *Inst.BinOp) InnerError!WValue {
+        const lhs = self.resolveInst(inst.lhs);
+        const rhs = self.resolveInst(inst.rhs);
+
+        try self.emitWValue(lhs);
+        try self.emitWValue(rhs);
+
+        const opcode: wasm.Opcode = switch (inst.base.ty.tag()) {
+            .u32, .i32 => .i32_sub,
+            .u64, .i64 => .i64_sub,
+            .f32 => .f32_sub,
+            .f64 => .f64_sub,
+            else => return self.fail(inst.base.src, "TODO - Implement wasm genSub for type '{s}'", .{inst.base.ty.tag()}),
+        };
+
+        try self.code.append(wasm.opcode(opcode));
+        return .none;
+    }
+
     fn emitConstant(self: *Context, inst: *Inst.Constant) InnerError!void {
         const writer = self.code.writer();
         switch (inst.base.ty.tag()) {
diff --git a/test/stage2/wasm.zig b/test/stage2/wasm.zig
index 51df6bccf0..d49598c855 100644
--- a/test/stage2/wasm.zig
+++ b/test/stage2/wasm.zig
@@ -121,6 +121,26 @@ pub fn addCases(ctx: *TestContext) !void {
             \\    return x + y;
             \\}
         , "35\n");
+
+        case.addCompareOutput(
+            \\export fn _start() u32 {
+            \\    var i: u32 = 20;
+            \\    i -= 5;
+            \\    return i;
+            \\}
+        , "15\n");
+
+        case.addCompareOutput(
+            \\export fn _start() u32 {
+            \\    var i: u32 = 5;
+            \\    i -= 3;
+            \\    var result: u32 = foo(i, 10);
+            \\    return result;
+            \\}
+            \\fn foo(x: u32, y: u32) u32 {
+            \\    return y - x;
+            \\}
+        , "8\n");
     }
 
     {