diff --git a/src/crewai/knowledge/source/base_file_knowledge_source.py b/src/crewai/knowledge/source/base_file_knowledge_source.py
index 5743b1704..ac345b6a6 100644
--- a/src/crewai/knowledge/source/base_file_knowledge_source.py
+++ b/src/crewai/knowledge/source/base_file_knowledge_source.py
@@ -26,9 +26,10 @@ class BaseFileKnowledgeSource(BaseKnowledgeSource, ABC):
     safe_file_paths: List[Path] = Field(default_factory=list)
 
     @field_validator("file_path", "file_paths", mode="before")
-    def validate_file_path(cls, v, values):
+    def validate_file_path(cls, v, info):
         """Validate that at least one of file_path or file_paths is provided."""
-        if v is None and ("file_path" not in values or values.get("file_path") is None):
+        # Single check if both are None, O(1) instead of nested conditions
+        if v is None and info.data.get("file_path" if info.field_name == "file_paths" else "file_paths") is None:
             raise ValueError("Either file_path or file_paths must be provided")
         return v
 
diff --git a/tests/knowledge/knowledge_test.py b/tests/knowledge/knowledge_test.py
index 366067587..6704d3031 100644
--- a/tests/knowledge/knowledge_test.py
+++ b/tests/knowledge/knowledge_test.py
@@ -584,3 +584,28 @@ def test_docling_source_with_local_file():
     docling_source = CrewDoclingSource(file_paths=[pdf_path])
     assert docling_source.file_paths == [pdf_path]
     assert docling_source.content is not None
+
+
+def test_file_path_validation():
+    """Test file path validation for knowledge sources."""
+    current_dir = Path(__file__).parent
+    pdf_path = current_dir / "crewai_quickstart.pdf"
+
+    # Test valid single file_path
+    source = PDFKnowledgeSource(file_path=pdf_path)
+    assert source.safe_file_paths == [pdf_path]
+
+    # Test valid file_paths list
+    source = PDFKnowledgeSource(file_paths=[pdf_path])
+    assert source.safe_file_paths == [pdf_path]
+
+    # Test both file_path and file_paths provided (should use file_paths)
+    source = PDFKnowledgeSource(file_path=pdf_path, file_paths=[pdf_path])
+    assert source.safe_file_paths == [pdf_path]
+
+    # Test neither file_path nor file_paths provided
+    with pytest.raises(
+        ValueError,
+        match="file_path/file_paths must be a Path, str, or a list of these types"
+    ):
+        PDFKnowledgeSource()