diff --git a/TrimSP.html b/TrimSP.html
index a39210c..261cd02 100644
--- a/TrimSP.html
+++ b/TrimSP.html
@@ -322,8 +322,16 @@
 	      </td>
 	    </tr>
 	    <tr>
-	      <td></td>
-	      <td></td>
+	      <td>
+		<input type="checkbox" id="flagICRU">
+	      </td>
+	      <td>
+	      	<details>
+		  <summary>Use ICRU parameters</summary>
+		  Force the TRIM.SP code to use stopping power
+		  parameters from the old ICRU tables. 
+		</details>
+	      </td>
 	      <td>
 	        <details>
 	          <summary>IRL</summary>
diff --git a/TrimSPlib.js b/TrimSPlib.js
index 33f351f..7939e7a 100644
--- a/TrimSPlib.js
+++ b/TrimSPlib.js
@@ -867,6 +867,9 @@ function prep_cfg(toggle) {
     for (key of parOther) {
 	All[key]= document.getElementById(key).value;
     }
+
+    // Check ICRU flag, if checked use it
+    All["flagICRU"] = document.getElementById("flagICRU").checked;
     
     // Construct full content of cfg file
     TrimSPcfg = FilesSec + LayersSec + ProjSec + ScanSec;
@@ -999,7 +1002,7 @@ function CreateInpFile(All) {
 	    All[LEkey+"E"+NEl]=ElE; // sprintf("%8.4f",$ElE);
 	    All["L"+i+"030"+NEl]=El030; // sprintf("%8.4f",$El030);
 	    
-	    let ElST = StoppingCoefficients(El);
+	    let ElST = StoppingCoefficients(El,All["flagICRU"]);
 	    let ElSTs = ElST.split(',');
 	    let j=1;
 	    for (let iElST of ElSTs) {