diff --git a/dlls/jscript/compile.c b/dlls/jscript/compile.c
index f96594862cd..bd11621f273 100644
--- a/dlls/jscript/compile.c
+++ b/dlls/jscript/compile.c
@@ -733,7 +733,7 @@ static HRESULT compile_literal(compiler_ctx_t *ctx, literal_t *literal)
             return E_OUTOFMEMORY;
 
         instr_ptr(ctx, instr)->arg1.str = str;
-        instr_ptr(ctx, instr)->arg2.lng = literal->u.regexp.flags;
+        instr_ptr(ctx, instr)->arg2.uint = literal->u.regexp.flags;
         return S_OK;
     }
     default:
diff --git a/dlls/jscript/engine.c b/dlls/jscript/engine.c
index 7d9b37a4a0e..bb42899feba 100644
--- a/dlls/jscript/engine.c
+++ b/dlls/jscript/engine.c
@@ -1206,7 +1206,7 @@ static HRESULT interp_str(exec_ctx_t *ctx)
 static HRESULT interp_regexp(exec_ctx_t *ctx)
 {
     const WCHAR *source = ctx->code->instrs[ctx->ip].arg1.str;
-    const LONG flags = get_op_int(ctx, 1);
+    const unsigned flags = get_op_uint(ctx, 1);
     jsdisp_t *regexp;
     VARIANT v;
     HRESULT hres;
diff --git a/dlls/jscript/engine.h b/dlls/jscript/engine.h
index 8c70783fab8..4a2c89e8cba 100644
--- a/dlls/jscript/engine.h
+++ b/dlls/jscript/engine.h
@@ -90,7 +90,7 @@ typedef struct {
     X(preinc,     1, ARG_INT,    0)        \
     X(push_except,1, ARG_ADDR,   ARG_BSTR) \
     X(push_scope, 1, 0,0)                  \
-    X(regexp,     1, ARG_STR,    ARG_INT)  \
+    X(regexp,     1, ARG_STR,    ARG_UINT) \
     X(rshift,     1, 0,0)                  \
     X(rshift2,    1, 0,0)                  \
     X(str,        1, ARG_STR,    0)        \