diff --git a/src/hb-cff-interp-cs-common.hh b/src/hb-cff-interp-cs-common.hh
index a2595baf7..283bdf14a 100644
--- a/src/hb-cff-interp-cs-common.hh
+++ b/src/hb-cff-interp-cs-common.hh
@@ -127,6 +127,7 @@ struct cs_interp_env_t : interp_env_t<ARG>
     seen_hintmask = false;
     hstem_count = 0;
     vstem_count = 0;
+    hintmask_size = 0;
     pt.init ();
     callStack.init ();
     globalSubrs.init (globalSubrs_);
diff --git a/test/api/test-ot-extents-cff b/test/api/test-ot-extents-cff
new file mode 100755
index 000000000..c9145aa54
Binary files /dev/null and b/test/api/test-ot-extents-cff differ
diff --git a/test/api/test-ot-extents-cff.dSYM/Contents/Info.plist b/test/api/test-ot-extents-cff.dSYM/Contents/Info.plist
new file mode 100644
index 000000000..ffdf1f2e5
--- /dev/null
+++ b/test/api/test-ot-extents-cff.dSYM/Contents/Info.plist
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+	<dict>
+		<key>CFBundleDevelopmentRegion</key>
+		<string>English</string>
+		<key>CFBundleIdentifier</key>
+		<string>com.apple.xcode.dsym.test-ot-extents-cff</string>
+		<key>CFBundleInfoDictionaryVersion</key>
+		<string>6.0</string>
+		<key>CFBundlePackageType</key>
+		<string>dSYM</string>
+		<key>CFBundleSignature</key>
+		<string>????</string>
+		<key>CFBundleShortVersionString</key>
+		<string>1.0</string>
+		<key>CFBundleVersion</key>
+		<string>1</string>
+	</dict>
+</plist>
diff --git a/test/api/test-ot-extents-cff.dSYM/Contents/Resources/DWARF/test-ot-extents-cff b/test/api/test-ot-extents-cff.dSYM/Contents/Resources/DWARF/test-ot-extents-cff
new file mode 100644
index 000000000..11616e451
Binary files /dev/null and b/test/api/test-ot-extents-cff.dSYM/Contents/Resources/DWARF/test-ot-extents-cff differ