diff --git a/Sources/GoogleAI/GenerativeModel.swift b/Sources/GoogleAI/GenerativeModel.swift
index efcc0df..7ed2016 100644
--- a/Sources/GoogleAI/GenerativeModel.swift
+++ b/Sources/GoogleAI/GenerativeModel.swift
@@ -55,7 +55,8 @@ public final class GenerativeModel {
   ///   - safetySettings: A value describing what types of harmful content your model should allow.
   ///   - tools: A list of ``Tool`` objects  that the model may use to generate the next response.
   ///   - systemInstruction: Instructions that direct the model to behave a certain way; currently
-  ///     only text content is supported, e.g., "You are a cat. Your name is Neko."
+  ///     only text content is supported, e.g.,
+  ///     `ModelContent(role: "system", parts: "You are a cat. Your name is Neko.")`.
   ///   - toolConfig: Tool configuration for any `Tool` specified in the request.
   ///   - requestOptions Configuration parameters for sending requests to the backend.
   public convenience init(name: String,
@@ -64,7 +65,7 @@ public final class GenerativeModel {
                           safetySettings: [SafetySetting]? = nil,
                           tools: [Tool]? = nil,
                           toolConfig: ToolConfig? = nil,
-                          systemInstruction: String...,
+                          systemInstruction: ModelContent? = nil,
                           requestOptions: RequestOptions = RequestOptions()) {
     self.init(
       name: name,
@@ -73,10 +74,7 @@ public final class GenerativeModel {
       safetySettings: safetySettings,
       tools: tools,
       toolConfig: toolConfig,
-      systemInstruction: ModelContent(
-        role: "system",
-        parts: systemInstruction.map { ModelContent.Part.text($0) }
-      ),
+      systemInstruction: systemInstruction,
       requestOptions: requestOptions,
       urlSession: .shared
     )
@@ -92,8 +90,7 @@ public final class GenerativeModel {
   ///   - safetySettings: A value describing what types of harmful content your model should allow.
   ///   - tools: A list of ``Tool`` objects  that the model may use to generate the next response.
   ///   - systemInstruction: Instructions that direct the model to behave a certain way; currently
-  ///     only text content is supported, e.g.,
-  ///     `ModelContent(role: "system", parts: "You are a cat. Your name is Neko.")`.
+  ///     only text content is supported, e.g., "You are a cat. Your name is Neko."
   ///   - toolConfig: Tool configuration for any `Tool` specified in the request.
   ///   - requestOptions Configuration parameters for sending requests to the backend.
   public convenience init(name: String,
@@ -102,7 +99,7 @@ public final class GenerativeModel {
                           safetySettings: [SafetySetting]? = nil,
                           tools: [Tool]? = nil,
                           toolConfig: ToolConfig? = nil,
-                          systemInstruction: ModelContent? = nil,
+                          systemInstruction: String...,
                           requestOptions: RequestOptions = RequestOptions()) {
     self.init(
       name: name,
@@ -111,7 +108,10 @@ public final class GenerativeModel {
       safetySettings: safetySettings,
       tools: tools,
       toolConfig: toolConfig,
-      systemInstruction: systemInstruction,
+      systemInstruction: ModelContent(
+        role: "system",
+        parts: systemInstruction.map { ModelContent.Part.text($0) }
+      ),
       requestOptions: requestOptions,
       urlSession: .shared
     )