diff --git a/extensions/spellcheck/hunspell/src/moz.build b/extensions/spellcheck/hunspell/src/moz.build
index 09764ec711..01f49ddd03 100644
--- a/extensions/spellcheck/hunspell/src/moz.build
+++ b/extensions/spellcheck/hunspell/src/moz.build
@@ -19,11 +19,18 @@ SOURCES += [
 
 DEFINES['BUILDING_LIBHUNSPELL'] = True
 
-SharedLibrary('hunspell')
+# Hunspell must be built into libxul on SunOS. See UXP Issue #2290.
+if CONFIG['OS_TARGET'] == 'SunOS':
 
-USE_LIBS += [
-    'mozglue'
-]
+    FINAL_LIBRARY = 'xul'
+
+else:
+
+    SharedLibrary('hunspell')
+
+    USE_LIBS += [
+       'mozglue'
+    ]
 
 LOCAL_INCLUDES += [
     '../glue',
diff --git a/toolkit/library/moz.build b/toolkit/library/moz.build
index 0b41c97cf1..69b207d77a 100644
--- a/toolkit/library/moz.build
+++ b/toolkit/library/moz.build
@@ -196,7 +196,7 @@ if CONFIG['MOZ_SYSTEM_JPEG']:
 
 if CONFIG['MOZ_SYSTEM_HUNSPELL']:
     OS_LIBS += CONFIG['MOZ_HUNSPELL_LIBS']
-else:
+elif CONFIG['OS_TARGET'] != 'SunOS':
     USE_LIBS += [ 'hunspell' ]
 
 if not CONFIG['MOZ_TREE_PIXMAN']: