diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/NimClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/NimClientCodegen.java
index 8e13aea833e3..35f3ff81c2d6 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/NimClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/NimClientCodegen.java
@@ -458,10 +458,13 @@ public CodegenModel fromModel(String name, Schema schema) {
         name = normalizeSchemaName(name);
         CodegenModel mdl = super.fromModel(name, schema);
 
-        // Detect integer enums - check both the schema type and the dataType
+        // Detect numeric enums - check both the schema type and the dataType
+        // Note: "number" type in OpenAPI can include integer values in enums
         if (mdl.isEnum) {
             String schemaType = schema != null ? schema.getType() : null;
-            if ("integer".equals(schemaType) || "int".equals(mdl.dataType) || "int64".equals(mdl.dataType)) {
+            if ("integer".equals(schemaType) || "number".equals(schemaType) ||
+                "int".equals(mdl.dataType) || "int64".equals(mdl.dataType) ||
+                "float".equals(mdl.dataType) || "float64".equals(mdl.dataType)) {
                 mdl.vendorExtensions.put("x-is-integer-enum", true);
             }
         }
@@ -606,22 +609,38 @@ public OperationsMap postProcessOperationsWithModels(OperationsMap objs, List<Mo
         return objs;
     }
 
+    /**
+     * Resolve a schema reference to its target schema.
+     * This is needed to properly detect nested maps/arrays when the schema is a $ref.
+     */
+    private Schema resolveSchema(Schema schema) {
+        if (schema != null && schema.get$ref() != null) {
+            Schema resolved = ModelUtils.getReferencedSchema(this.openAPI, schema);
+            return resolved != null ? resolved : schema;
+        }
+        return schema;
+    }
+
     @Override
     public String getTypeDeclaration(Schema p) {
-        if (ModelUtils.isArraySchema(p)) {
-            Schema inner = ModelUtils.getSchemaItems(p);
+        // Resolve the schema to check for nested maps/arrays - refs that point to map/array schemas
+        Schema resolved = resolveSchema(p);
+
+        if (ModelUtils.isArraySchema(resolved)) {
+            Schema inner = ModelUtils.getSchemaItems(resolved);
             if (inner == null) {
                 return null;
             }
             return "seq[" + getTypeDeclaration(inner) + "]";
-        } else if (ModelUtils.isMapSchema(p)) {
-            Schema inner = ModelUtils.getAdditionalProperties(p);
+        } else if (ModelUtils.isMapSchema(resolved)) {
+            Schema inner = ModelUtils.getAdditionalProperties(resolved);
             if (inner == null) {
                 inner = new StringSchema();
             }
             return "Table[string, " + getTypeDeclaration(inner) + "]";
         }
 
+        // For non-containers, use the original schema to preserve model names
         String schemaType = getSchemaType(p);
         if (typeMapping.containsKey(schemaType)) {
             return typeMapping.get(schemaType);
@@ -719,10 +738,17 @@ private String sanitizeNimIdentifier(String name) {
 
     @Override
     public String toEnumVarName(String name, String datatype) {
+        // Handle negative numbers by prefixing with "Neg" to avoid collisions
+        // e.g., -1 and 1 would both become `1` without this, causing invalid syntax
+        if (name.startsWith("-")) {
+            name = "Neg" + name.substring(1);
+        }
+
         name = name.replace(" ", "_");
         name = StringUtils.camelize(name);
 
-        // starts with number or contains any character not allowed,see
+        // starts with number or contains any character not allowed, see
+        // https://nim-lang.org/docs/manual.html#lexical-analysis-identifiers-amp-keywords
         if (isValidIdentifier(name)) {
             return name;
         } else {
diff --git a/modules/openapi-generator/src/test/resources/3_0/nim/petstore.yaml b/modules/openapi-generator/src/test/resources/3_0/nim/petstore.yaml
index 23c6f0fe4e8c..6df5edfcc430 100644
--- a/modules/openapi-generator/src/test/resources/3_0/nim/petstore.yaml
+++ b/modules/openapi-generator/src/test/resources/3_0/nim/petstore.yaml
@@ -1020,3 +1020,29 @@ components:
           type: array
           items:
             $ref: '#/components/schemas/PetReview'
+
+    # Test numeric enum with negative values
+    DigestEmailFrequency:
+      description: Email digest frequency with negative value for disabled
+      type: number
+      enum: [-1, 0, 1, 2]
+
+    # Test nested maps (map of maps)
+    StringMap:
+      description: A simple string to string map
+      type: object
+      additionalProperties:
+        type: string
+    NestedStringMap:
+      description: A nested map (string to map of string to string)
+      type: object
+      additionalProperties:
+        $ref: '#/components/schemas/StringMap'
+    PetStatistics:
+      description: Statistics about a pet including nested map for health records
+      type: object
+      properties:
+        groomingHistory:
+          $ref: '#/components/schemas/StringMap'
+        healthRecords:
+          $ref: '#/components/schemas/NestedStringMap'
diff --git a/samples/client/petstore/nim/.openapi-generator/FILES b/samples/client/petstore/nim/.openapi-generator/FILES
index f8e488383817..83c3ca42d9c5 100644
--- a/samples/client/petstore/nim/.openapi-generator/FILES
+++ b/samples/client/petstore/nim/.openapi-generator/FILES
@@ -7,6 +7,7 @@ petstore/apis/api_user.nim
 petstore/models/model_any_type.nim
 petstore/models/model_api_response.nim
 petstore/models/model_category.nim
+petstore/models/model_digest_email_frequency.nim
 petstore/models/model_get_pet_reviews200response.nim
 petstore/models/model_get_pet_reviews_response_with_presence.nim
 petstore/models/model_get_pet_stats200response.nim
@@ -23,6 +24,7 @@ petstore/models/model_pet_positions.nim
 petstore/models/model_pet_priority.nim
 petstore/models/model_pet_review.nim
 petstore/models/model_pet_reviews_response.nim
+petstore/models/model_pet_statistics.nim
 petstore/models/model_record_string_before_string_or_null_after_string_or_null_value.nim
 petstore/models/model_tag.nim
 petstore/models/model_unfavorite_pet_request.nim
diff --git a/samples/client/petstore/nim/petstore.nim b/samples/client/petstore/nim/petstore.nim
index 6a0b825c31d8..dee94daf948f 100644
--- a/samples/client/petstore/nim/petstore.nim
+++ b/samples/client/petstore/nim/petstore.nim
@@ -10,6 +10,7 @@
 # Models
 import petstore/models/model_api_response
 import petstore/models/model_category
+import petstore/models/model_digest_email_frequency
 import petstore/models/model_get_pet_reviews200response
 import petstore/models/model_get_pet_reviews_response_with_presence
 import petstore/models/model_get_pet_stats200response
@@ -25,6 +26,7 @@ import petstore/models/model_pet_positions
 import petstore/models/model_pet_priority
 import petstore/models/model_pet_review
 import petstore/models/model_pet_reviews_response
+import petstore/models/model_pet_statistics
 import petstore/models/model_record_string_before_string_or_null_after_string_or_null_value
 import petstore/models/model_tag
 import petstore/models/model_unfavorite_pet_request
@@ -32,6 +34,7 @@ import petstore/models/model_user
 
 export model_api_response
 export model_category
+export model_digest_email_frequency
 export model_get_pet_reviews200response
 export model_get_pet_reviews_response_with_presence
 export model_get_pet_stats200response
@@ -47,6 +50,7 @@ export model_pet_positions
 export model_pet_priority
 export model_pet_review
 export model_pet_reviews_response
+export model_pet_statistics
 export model_record_string_before_string_or_null_after_string_or_null_value
 export model_tag
 export model_unfavorite_pet_request
diff --git a/samples/client/petstore/nim/petstore/models/model_digest_email_frequency.nim b/samples/client/petstore/nim/petstore/models/model_digest_email_frequency.nim
new file mode 100644
index 000000000000..92eaba47ee9f
--- /dev/null
+++ b/samples/client/petstore/nim/petstore/models/model_digest_email_frequency.nim
@@ -0,0 +1,50 @@
+#
+# OpenAPI Petstore
+# 
+# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+# The version of the OpenAPI document: 1.0.0
+# 
+# Generated by: https://openapi-generator.tech
+#
+
+import json
+import tables
+import marshal
+import options
+
+
+type DigestEmailFrequency* {.pure.} = enum
+  Neg1
+  `0`
+  `1`
+  `2`
+
+func `%`*(v: DigestEmailFrequency): JsonNode =
+  result = case v:
+    of DigestEmailFrequency.Neg1: %(-1)
+    of DigestEmailFrequency.`0`: %(0)
+    of DigestEmailFrequency.`1`: %(1)
+    of DigestEmailFrequency.`2`: %(2)
+
+func `$`*(v: DigestEmailFrequency): string =
+  result = case v:
+    of DigestEmailFrequency.Neg1: $(-1)
+    of DigestEmailFrequency.`0`: $(0)
+    of DigestEmailFrequency.`1`: $(1)
+    of DigestEmailFrequency.`2`: $(2)
+proc to*(node: JsonNode, T: typedesc[DigestEmailFrequency]): DigestEmailFrequency =
+  if node.kind != JInt:
+    raise newException(ValueError, "Expected integer for enum DigestEmailFrequency, got " & $node.kind)
+  let intVal = node.getInt()
+  case intVal:
+  of -1:
+    return DigestEmailFrequency.Neg1
+  of 0:
+    return DigestEmailFrequency.`0`
+  of 1:
+    return DigestEmailFrequency.`1`
+  of 2:
+    return DigestEmailFrequency.`2`
+  else:
+    raise newException(ValueError, "Invalid enum value for DigestEmailFrequency: " & $intVal)
+
diff --git a/samples/client/petstore/nim/petstore/models/model_pet_statistics.nim b/samples/client/petstore/nim/petstore/models/model_pet_statistics.nim
new file mode 100644
index 000000000000..355b4c3a4fd7
--- /dev/null
+++ b/samples/client/petstore/nim/petstore/models/model_pet_statistics.nim
@@ -0,0 +1,20 @@
+#
+# OpenAPI Petstore
+# 
+# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+# The version of the OpenAPI document: 1.0.0
+# 
+# Generated by: https://openapi-generator.tech
+#
+
+import json
+import tables
+import marshal
+import options
+
+
+type PetStatistics* = object
+  ## Statistics about a pet including nested map for health records
+  groomingHistory*: Option[Table[string, string]] ## A simple string to string map
+  healthRecords*: Option[Table[string, Table[string, string]]] ## A nested map (string to map of string to string)
+