diff --git a/src/extractors.ts b/src/extractors.ts
index df04083..4160fde 100644
--- a/src/extractors.ts
+++ b/src/extractors.ts
@@ -104,7 +104,7 @@ ${content}
 `;
 
   if (dataToEnrich) {
-    promptTemplate += `Format: JSON
+    promptTemplate += `Original JSON object:
 ---
 ${JSON.stringify(dataToEnrich, null, 2)}
 ------
@@ -116,9 +116,9 @@ Your task is: ${extractionTask}
 ## Guidelines:
 1. Extract ONLY information explicitly stated in the context
 2. Enrich the original JSON object with information from the context
-3. Fill additional fields based on relevant information in the context
-4. Do not make assumptions or infer missing data
-5. Leave fields empty when information is not present or you are uncertain
+3. Do not remove any fields from the original JSON object
+4. Only update existing fields and fill in additional fields if new and relevant information is available in the context
+5. Do not make assumptions or infer missing data
 6. Do not include information that appears incomplete or truncated
 
 `;
diff --git a/tests/unit/extractors.test.ts b/tests/unit/extractors.test.ts
index b0f6da3..a27d4db 100644
--- a/tests/unit/extractors.test.ts
+++ b/tests/unit/extractors.test.ts
@@ -306,7 +306,7 @@ describe("extractors", () => {
       expect(prompt).toContain("Context information is below:");
       expect(prompt).toContain("Format: markdown");
       expect(prompt).toContain("Some markdown content");
-      expect(prompt).toContain("Format: JSON");
+      expect(prompt).toContain("Original JSON object");
       expect(prompt).toContain(JSON.stringify(dataToEnrich, null, 2));
       expect(prompt).toContain(
         "You are a data extraction assistant that extracts structured information from the above context in markdown and JSON"
@@ -315,7 +315,7 @@ describe("extractors", () => {
         "Enrich the original JSON object with information from the context"
       );
       expect(prompt).toContain(
-        "Fill additional fields based on relevant information in the context"
+        "Only update existing fields and fill in additional fields if new and relevant information is available in the context"
       );
       expect(prompt).toContain(
         "Return only the structured data in valid JSON format"