diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index 22d5a1604..70ade2c5b 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -1122,6 +1122,12 @@ class PartialEvaluator {
         case "Type":
           break;
         case "LW":
+          if (typeof value !== "number") {
+            warn(`Invalid LW (line width): ${value}`);
+            break;
+          }
+          gStateObj.push([key, Math.abs(value)]);
+          break;
         case "LC":
         case "LJ":
         case "ML":
@@ -2212,6 +2218,18 @@ class PartialEvaluator {
               })
             );
             return;
+          case OPS.setLineWidth: {
+            // The thickness should be a non-negative number, as per spec.
+            // When the value is negative, Acrobat and Poppler take the absolute
+            // value while PDFium takes the max of 0 and the value.
+            const [thickness] = args;
+            if (typeof thickness !== "number") {
+              warn(`Invalid setLineWidth: ${thickness}`);
+              continue;
+            }
+            args[0] = Math.abs(thickness);
+            break;
+          }
           case OPS.moveTo:
           case OPS.lineTo:
           case OPS.curveTo:
diff --git a/test/pdfs/.gitignore b/test/pdfs/.gitignore
index 900b36d08..2b06b3a4e 100644
--- a/test/pdfs/.gitignore
+++ b/test/pdfs/.gitignore
@@ -711,3 +711,4 @@
 !issue19505.pdf
 !colors.pdf
 !red_stamp.pdf
+!issue19633.pdf
diff --git a/test/pdfs/issue19633.pdf b/test/pdfs/issue19633.pdf
new file mode 100755
index 000000000..34ca03ffa
Binary files /dev/null and b/test/pdfs/issue19633.pdf differ
diff --git a/test/test_manifest.json b/test/test_manifest.json
index bfa914535..e660566a9 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -11971,5 +11971,12 @@
     "rounds": 1,
     "link": true,
     "type": "eq"
+  },
+  {
+    "id": "issue19633",
+    "file": "pdfs/issue19633.pdf",
+    "md5": "9993aa298c0214a3d3ff5f90ce0d40bb",
+    "rounds": 1,
+    "type": "eq"
   }
 ]