diff --git a/pdfsearch/pdfsearch.py b/pdfsearch/pdfsearch.py
index 1c7d403..6ae045a 100644
--- a/pdfsearch/pdfsearch.py
+++ b/pdfsearch/pdfsearch.py
@@ -43,6 +43,16 @@ def search_string(pattern, string, match_object, context_length):
 def search_pdf(pdf_name, search_patterns, context_length):
     """Search for text strings inside a pdf.
 
+    Search patterns should be lowercase, unless case-sensitivity is important.
+
+    'ph' will match:
+       - photograph
+       - PHANTOM
+       - pH
+
+    'pH' will match:
+       - pH
+
     Args:
         pdf_name:        path to pdf file
         search_patterns: list of re search patterns
@@ -80,7 +90,7 @@ def search_pdf(pdf_name, search_patterns, context_length):
                     matches = re.finditer(pattern, page_text.lower())
                 else:
                     matches = re.finditer(pattern, page_text)
-                    
+
                 for match in matches:
                     whole_word, context = search_string(
                         pattern, page_text, match, context_length)