diff --git a/lib/svg-symbol-metadata.test.ts b/lib/svg-symbol-metadata.test.ts
index 5ed1110..3536f4d 100644
--- a/lib/svg-symbol-metadata.test.ts
+++ b/lib/svg-symbol-metadata.test.ts
@@ -23,8 +23,11 @@ describe("validateSvgSymbolMetadata()", () => {
         always_be_nested: true,
       })
     ).toEqual({
-      always_nest: true,
-      always_be_nested: true,
+      metadata: {
+        always_nest: true,
+        always_be_nested: true,
+      },
+      unknownProperties: [],
     });
   });
 
@@ -37,10 +40,14 @@ describe("validateSvgSymbolMetadata()", () => {
   });
 
   it("raises errors when a property is unrecognized", () => {
-    expect(() =>
+    expect(
       validateSvgSymbolMetadata({
+        always_nest: true,
         blarp: true,
       })
-    ).toThrow('Unrecognized SVG symbol metadata property "blarp"');
+    ).toEqual({
+      metadata: { always_nest: true },
+      unknownProperties: ["blarp"],
+    });
   });
 });
diff --git a/lib/svg-symbol-metadata.ts b/lib/svg-symbol-metadata.ts
index c8700c9..c871f52 100644
--- a/lib/svg-symbol-metadata.ts
+++ b/lib/svg-symbol-metadata.ts
@@ -25,8 +25,11 @@ function isSvgSymbolMetadataBoolean(
 
 export type SvgSymbolMetadata = SvgSymbolMetadataBooleans;
 
-export function validateSvgSymbolMetadata(obj: any): SvgSymbolMetadata {
-  const result: SvgSymbolMetadata = {};
+export function validateSvgSymbolMetadata(
+  obj: any
+): { metadata: SvgSymbolMetadata; unknownProperties: string[] } {
+  const metadata: SvgSymbolMetadata = {};
+  const unknownProperties: string[] = [];
   for (let key in obj) {
     const value: unknown = obj[key];
     if (isSvgSymbolMetadataBoolean(key)) {
@@ -35,10 +38,10 @@ export function validateSvgSymbolMetadata(obj: any): SvgSymbolMetadata {
           `Expected "${key}" to be a boolean, but it is a ${typeof value}!`
         );
       }
-      result[key] = value;
+      metadata[key] = value;
     } else {
-      throw new Error(`Unrecognized SVG symbol metadata property "${key}"`);
+      unknownProperties.push(key);
     }
   }
-  return result;
+  return { metadata, unknownProperties };
 }
diff --git a/lib/vocabulary-builder.ts b/lib/vocabulary-builder.ts
index 67b8b07..fe0d8e2 100644
--- a/lib/vocabulary-builder.ts
+++ b/lib/vocabulary-builder.ts
@@ -127,7 +127,17 @@ export function build() {
       });
       const symbol = convertSvgMarkupToSymbolData(filename, svgMarkup);
       if (metaToml) {
-        symbol.meta = validateSvgSymbolMetadata(toml.parse(metaToml));
+        const { metadata, unknownProperties } = validateSvgSymbolMetadata(
+          toml.parse(metaToml)
+        );
+        symbol.meta = metadata;
+        if (unknownProperties.length) {
+          console.log(
+            `WARNING: Found unknown metadata properties ${unknownProperties.join(
+              ", "
+            )}.`
+          );
+        }
       }
       vocab.push(symbol);
     }