diff --git a/dlls/jscript/engine.c b/dlls/jscript/engine.c
index d9e6353f03e..5b175721dbd 100644
--- a/dlls/jscript/engine.c
+++ b/dlls/jscript/engine.c
@@ -1536,10 +1536,39 @@ HRESULT plus_expression_eval(exec_ctx_t *ctx, expression_t *expr, DWORD flags, j
     return E_NOTIMPL;
 }
 
-HRESULT post_increment_expression_eval(exec_ctx_t *ctx, expression_t *expr, DWORD flags, jsexcept_t *ei, exprval_t *ret)
+/* ECMA-262 3rd Edition    11.3.1 */
+HRESULT post_increment_expression_eval(exec_ctx_t *ctx, expression_t *_expr, DWORD flags, jsexcept_t *ei, exprval_t *ret)
 {
-    FIXME("\n");
-    return E_NOTIMPL;
+    unary_expression_t *expr = (unary_expression_t*)_expr;
+    VARIANT val, num;
+    exprval_t exprval;
+    HRESULT hres;
+
+    TRACE("\n");
+
+    hres = expr_eval(ctx, expr->expression, EXPR_NEWREF, ei, &exprval);
+    if(FAILED(hres))
+        return hres;
+
+    hres = exprval_value(ctx->parser->script, &exprval, ei, &val);
+    if(SUCCEEDED(hres)) {
+        hres = to_number(ctx->parser->script, &val, ei, &num);
+        VariantClear(&val);
+    }
+
+    if(SUCCEEDED(hres)) {
+        VARIANT inc;
+        num_set_val(&inc, num_val(&num)+1.0);
+        hres = put_value(ctx->parser->script, &exprval, &inc, ei);
+    }
+
+    exprval_release(&exprval);
+    if(FAILED(hres))
+        return hres;
+
+    ret->type = EXPRVAL_VARIANT;
+    ret->u.var = num;
+    return S_OK;
 }
 
 HRESULT post_decrement_expression_eval(exec_ctx_t *ctx, expression_t *expr, DWORD flags, jsexcept_t *ei, exprval_t *ret)
diff --git a/dlls/jscript/tests/lang.js b/dlls/jscript/tests/lang.js
index ef3e4548b06..7f51dde7774 100644
--- a/dlls/jscript/tests/lang.js
+++ b/dlls/jscript/tests/lang.js
@@ -228,5 +228,7 @@ ok(++tmp === 2, "++tmp (1) is not 2");
 ok(tmp === 2, "incremented tmp is not 2");
 ok(--tmp === 1, "--tmp (2) is not 1");
 ok(tmp === 1, "decremented tmp is not 1");
+ok(tmp++ === 1, "tmp++ (1) is not 1");
+ok(tmp === 2, "incremented tmp(1) is not 2");
 
 reportSuccess();