diff --git a/src/lint/ArcanistLintMessage.php b/src/lint/ArcanistLintMessage.php
--- a/src/lint/ArcanistLintMessage.php
+++ b/src/lint/ArcanistLintMessage.php
@@ -72,24 +72,7 @@
   }
 
   public function setLine($line) {
-    if ($line === null) {
-      // This just means that we don't have any line information.
-    } else {
-      // For compatibility, accept digit strings since a lot of linters pass
-      // line numbers that they have parsed from command output or XML, which
-      // won't be properly typed.
-      if (is_string($line) && preg_match('/^\d+\z/', $line)) {
-        $line = (int)$line;
-      }
-
-      if (!is_int($line)) {
-        throw new Exception(
-          pht(
-            'Parameter passed to setLine() must be an integer.'));
-      }
-    }
-
-    $this->line = $line;
+    $this->line = $this->validateInteger($line, 'setLine');
     return $this;
   }
 
@@ -98,7 +81,7 @@
   }
 
   public function setChar($char) {
-    $this->char = $char;
+    $this->char = $this->validateInteger($char, 'setChar');
     return $this;
   }
 
@@ -242,4 +225,35 @@
     return $this->bypassChangedLineFiltering;
   }
 
+  /**
+   * Validate an integer-like value, returning a strict integer.
+   *
+   * Further on, the pipeline is strict about types. We want to be a little
+   * less strict in linters themselves, since they often parse command line
+   * output or XML and will end up with string representations of numbers.
+   *
+   * @param mixed Integer or digit string.
+   * @return int Integer.
+   */
+  private function validateInteger($value, $caller) {
+    if ($value === null) {
+      // This just means that we don't have any information.
+      return null;
+    }
+
+    // Strings like "234" are fine, coerce them to integers.
+    if (is_string($value) && preg_match('/^\d+\z/', $value)) {
+      $value = (int)$value;
+    }
+
+    if (!is_int($value)) {
+      throw new Exception(
+        pht(
+          'Parameter passed to "%s" must be an integer.',
+          $caller.'()'));
+    }
+
+    return $value;
+  }
+
 }