diff --git a/3rdparty/json11/json11.cpp b/3rdparty/json11/json11.cpp
index 88024e92..faa6cf64 100644
--- a/3rdparty/json11/json11.cpp
+++ b/3rdparty/json11/json11.cpp
@@ -24,7 +24,8 @@
 #include <cmath>
 #include <cstdlib>
 #include <cstdio>
-#include <limits>
+#include <climits>
+#include <cerrno>
 
 namespace json11 {
 
@@ -589,9 +590,11 @@ struct JsonParser final {
             return fail("invalid " + esc(str[i]) + " in number");
         }
 
-        if (str[i] != '.' && str[i] != 'e' && str[i] != 'E'
-                && (i - start_pos) <= static_cast<size_t>(std::numeric_limits<int>::digits10)) {
-            return std::atoi(str.c_str() + start_pos);
+        if (str[i] != '.' && str[i] != 'e' && str[i] != 'E') {
+            errno = 0;
+            long val = std::strtol(str.c_str() + start_pos, nullptr, 0);
+            if (!errno && val >= INT_MIN && val <= INT_MAX)
+                return int(val);
         }
 
         // Decimal part
diff --git a/frontend/json_frontend.cc b/frontend/json_frontend.cc
index f1310e71..136786fc 100644
--- a/frontend/json_frontend.cc
+++ b/frontend/json_frontend.cc
@@ -105,10 +105,14 @@ struct JsonFrontendImpl
 
     Property parse_property(const Json &val) const
     {
-        if (val.is_number())
+        if (val.is_number()) {
+            if (val.int_value() != val.number_value())
+                log_error("Found an out-of-range integer parameter in the JSON file.\n"
+                          "Please regenerate the input file with an up-to-date version of yosys.\n");
             return Property(val.int_value(), 32);
-        else
+        } else {
             return Property::from_string(val.string_value());
+        }
     }
 
     template <typename TFunc> void foreach_attr(const Json &obj, TFunc Func) const
diff --git a/json/jsonwrite.cc b/json/jsonwrite.cc
index 477bfca5..d4a62a5a 100644
--- a/json/jsonwrite.cc
+++ b/json/jsonwrite.cc
@@ -45,15 +45,6 @@ std::string get_string(std::string str)
 
 std::string get_name(IdString name, Context *ctx) { return get_string(name.c_str(ctx)); }
 
-void write_parameter_value(std::ostream &f, const Property &value)
-{
-    if (value.size() == 32 && value.is_fully_def()) {
-        f << stringf("%d", value.as_int64());
-    } else {
-        f << get_string(value.to_string());
-    }
-}
-
 void write_parameters(std::ostream &f, Context *ctx, const std::unordered_map<IdString, Property> &parameters,
                       bool for_module = false)
 {
@@ -61,7 +52,7 @@ void write_parameters(std::ostream &f, Context *ctx, const std::unordered_map<Id
     for (auto &param : parameters) {
         f << stringf("%s\n", first ? "" : ",");
         f << stringf("        %s%s: ", for_module ? "" : "    ", get_name(param.first, ctx).c_str());
-        write_parameter_value(f, param.second);
+        f << get_string(param.second.to_string());
         first = false;
     }
 }