diff --git a/make.sh b/make.sh
index 614c192..edf1080 100755
--- a/make.sh
+++ b/make.sh
@@ -4,6 +4,7 @@ FILENAME="ResearchProposal"
 
 IN="${FILENAME}.md"
 OUT="${FILENAME}.pdf"
+OUT_MOD="${FILENAME}-Erkl.pdf"
 
 # Generate the PDF from Markdown
 echo "Generating PDF..."
@@ -22,7 +23,7 @@ fi
 
 # Insert Erklärung.pdf at the end of the PDF
 echo "Modifying the PDF..."
-./modify-pdf.sh "$OUT" "resources/Erklärung.pdf" "$OUT"
+./modify-pdf.sh "$OUT" "resources/Erklärung.pdf" "$OUT_MOD"
 
 # remove last page for osf.io
 echo "Removing last page for OSF.io output and saving to OSF-$OUT"
diff --git a/modify-pdf.sh b/modify-pdf.sh
index 34788a7..f155216 100755
--- a/modify-pdf.sh
+++ b/modify-pdf.sh
@@ -17,6 +17,30 @@ input_pdf="$1"
 insert_pdf="$2"
 output_pdf="$3"
 
+# Check if input and insert PDFs exist
+if [ ! -f "$input_pdf" ]; then
+    echo "Error: Input PDF '$input_pdf' not found."
+    exit 1
+fi
+
+if [ ! -f "$insert_pdf" ]; then
+    echo "Error: Insert PDF '$insert_pdf' not found. Deleting the last page from input PDF."
+
+    # Get the number of pages in the input PDF
+    num_pages=$(pdftk "$input_pdf" dump_data | grep NumberOfPages | awk '{print $2}')
+
+    if [ -z "$num_pages" ] || [ "$num_pages" -le 1 ]; then
+        echo "Error: Input PDF has insufficient pages or unable to determine the number of pages."
+        exit 1
+    fi
+
+    # Remove the last page and save as output
+    pdftk "$input_pdf" cat 1-$(($num_pages - 1)) output "$output_pdf"
+
+    echo "Removed the last page from '$input_pdf' and saved as '$output_pdf'."
+    exit 1
+fi
+
 # Get the number of pages in the input PDF
 num_pages=$(pdftk "$input_pdf" dump_data | grep NumberOfPages | awk '{print $2}')
 
@@ -34,4 +58,5 @@ pdftk temp_removed_last.pdf "$insert_pdf" cat output "$output_pdf"
 # Clean up temporary files
 rm -f temp_removed_last.pdf
 
-echo "Successfully created $output_pdf by replacing the last page with $insert_pdf."
+# Success message
+echo "Successfully created '$output_pdf' by replacing the last page with '$insert_pdf'."
\ No newline at end of file