diff --git a/src/us/kolmafia/multitool/Multitool.java b/src/us/kolmafia/multitool/Multitool.java
index f645ca0..d836563 100644
--- a/src/us/kolmafia/multitool/Multitool.java
+++ b/src/us/kolmafia/multitool/Multitool.java
@@ -146,17 +146,10 @@ private static ToolData processTool(String toolName) {
     int localVersion = 0;
     for (String systemJarName : locals) {
       String jarName = systemJarName.toLowerCase();
-      int i = jarName.indexOf(toolName);
-      String hold = jarName.substring(i + toolName.length() + 1);
-      i = hold.indexOf(".jar");
-      hold = hold.substring(0, i);
-      if (hold.contains("-m")) {
-        i = hold.indexOf("-m");
-        hold = hold.substring(0, i);
-        retVal.setLocalModificationFound(true);
-      }
+      VersionData verDat = getVersionDataFromFilename(jarName, toolName);
       runMe = systemJarName;
-      localVersion = Integer.parseInt(hold);
+      localVersion = verDat.getVersion();
+      retVal.setLocalModificationFound(verDat.isModified());
     }
     retVal.setCurrentVersion(localVersion);
     retVal.setNeedToDownload(localVersion < version);
@@ -216,7 +209,7 @@ private static int getLatestReleaseVersion(String tool) {
 
   /**
    * Uses an opened input stream to determine the latest version of a tool in a remote repository.
-   * Caller needs to Closes the input stream.
+   * Caller needs to close the input stream.
    *
    * @param is Successfully opened input stream to remote repository.
    * @return latest version in repository or zero
@@ -304,4 +297,33 @@ public static void initLogOrExit() {
       System.exit(0);
     }
   }
+
+  static VersionData getVersionDataFromFilename(String jarName, String toolName) {
+    VersionData noResult = new VersionData(0, false);
+    jarName = jarName.toLowerCase();
+    toolName = toolName.toLowerCase();
+    String dotJar = ".jar";
+    if (!jarName.startsWith(toolName)) return noResult;
+    if (!jarName.endsWith(dotJar)) return noResult;
+    boolean mod = false;
+    int i = jarName.indexOf(toolName);
+    String hold = jarName.substring(i + toolName.length());
+    if (!hold.startsWith("-")) return noResult;
+    hold = hold.substring(1);
+    i = hold.indexOf(".jar");
+    hold = hold.substring(0, i);
+    if (hold.contains("-m")) {
+      i = hold.indexOf("-m");
+      hold = hold.substring(0, i);
+      mod = true;
+    }
+    boolean isNumeric = hold.chars().allMatch(Character::isDigit);
+    if (!isNumeric) return noResult;
+    try {
+      int verVal = Integer.parseInt(hold);
+      return new VersionData(verVal, mod);
+    } catch (NumberFormatException e) {
+      return noResult;
+    }
+  }
 }
diff --git a/src/us/kolmafia/multitool/VersionData.java b/src/us/kolmafia/multitool/VersionData.java
new file mode 100644
index 0000000..d7cda04
--- /dev/null
+++ b/src/us/kolmafia/multitool/VersionData.java
@@ -0,0 +1,19 @@
+package us.kolmafia.multitool;
+
+public class VersionData {
+  private final int version;
+  private final boolean modified;
+
+  public VersionData(int ver, boolean mod) {
+    this.version = ver;
+    this.modified = mod;
+  }
+
+  public int getVersion() {
+    return version;
+  }
+
+  public boolean isModified() {
+    return modified;
+  }
+}
diff --git a/test/us/kolmafia/multitool/MultitoolTest.java b/test/us/kolmafia/multitool/MultitoolTest.java
index 9b7796c..4bf704a 100644
--- a/test/us/kolmafia/multitool/MultitoolTest.java
+++ b/test/us/kolmafia/multitool/MultitoolTest.java
@@ -11,6 +11,7 @@
 import static us.kolmafia.multitool.Constants.ROOT_LOCATION;
 import static us.kolmafia.multitool.Multitool.cleanPath;
 import static us.kolmafia.multitool.Multitool.cwd;
+import static us.kolmafia.multitool.Multitool.getVersionDataFromFilename;
 import static us.kolmafia.multitool.Multitool.getVersionFromInputStream;
 import static us.kolmafia.multitool.Multitool.initLogOrExit;
 import static us.kolmafia.multitool.Multitool.logFileName;
@@ -28,6 +29,8 @@
 import java.util.List;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
 class MultitoolTest {
 
@@ -50,14 +53,7 @@ public void itShouldFindNoFiles() {
 
   private boolean validateDestination(Path destination) {
     File dFile = destination.toFile();
-    boolean retVal = dFile.exists();
-    if (retVal) {
-      retVal = dFile.isDirectory();
-      if (retVal) {
-        retVal = dFile.canWrite();
-      }
-    }
-    return retVal;
+    return dFile.exists() && dFile.isDirectory() && dFile.canWrite();
   }
 
   @Test
@@ -80,7 +76,7 @@ public void itShouldFindFilesThatWerePutThere() {
       try {
         copy(sPath, dPath, StandardCopyOption.REPLACE_EXISTING);
       } catch (IOException e) {
-        throw new RuntimeException(e);
+        fail(e.getMessage());
       }
     }
     inDir = processDirectory(KOLMAFIA_NAME);
@@ -131,4 +127,22 @@ public void itShouldGetKoLmafiaVersion() {
     }
     assertEquals(28465, getVersionFromInputStream(fs));
   }
+
+  @ParameterizedTest
+  @CsvSource({
+    "kolmafia, kolmafia, 0, false",
+    "kolmafia-123, kolmafia, 0, false",
+    "kolmafia123.jar, kolmafia, 0, false",
+    "kolmafia-123.jar, kolmafia, 123, false",
+    "kolmafia-123-m.jar, kolmafia, 123, true",
+    "kolmafia-123-.jar, kolmafia, 0, false",
+    "kolmafia-latest.jar, kolmafia, 0, false",
+    "notatool-123.jar, kolmafia, 0, false"
+  })
+  public void itShouldGetVersions(
+      String jarName, String toolName, int expectedVersion, boolean expectedmod) {
+    VersionData vd = getVersionDataFromFilename(jarName, toolName);
+    assertEquals(expectedVersion, vd.getVersion());
+    assertEquals(expectedmod, vd.isModified());
+  }
 }
diff --git a/test/us/kolmafia/multitool/VersionDataTest.java b/test/us/kolmafia/multitool/VersionDataTest.java
new file mode 100644
index 0000000..53867c3
--- /dev/null
+++ b/test/us/kolmafia/multitool/VersionDataTest.java
@@ -0,0 +1,14 @@
+package us.kolmafia.multitool;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class VersionDataTest {
+  @Test
+  public void itShouldGetWhatWasSet() {
+    VersionData vd = new VersionData(1066, true);
+    assertEquals(1066, vd.getVersion());
+    assertTrue(vd.isModified());
+  }
+}