diff --git a/.gitignore b/.gitignore
index 238e9cb..5d12d15 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,5 +10,5 @@ parsertrace
 parsertrace_g
 *.mk
 *.Makefile
-*.so
+*.so.*
 *.a
diff --git a/Makefile b/Makefile
index 64e5c2f..02182b1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,26 @@
+# Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to
+# deal in the Software without restriction, including without limitation the
+# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+# sell copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+
+PLATFORM ?= $(shell sh -c 'uname -s | tr "[A-Z]" "[a-z]"')
+SONAME ?= libhttp_parser.so.2.1
+
 CC?=gcc
 AR?=ar
 
@@ -12,6 +35,13 @@ CFLAGS_DEBUG = $(CFLAGS) -O0 -g $(CFLAGS_DEBUG_EXTRA)
 CFLAGS_FAST = $(CFLAGS) -O3 $(CFLAGS_FAST_EXTRA)
 CFLAGS_LIB = $(CFLAGS_FAST) -fPIC
 
+LDFLAGS_LIB = $(LDFLAGS) -shared
+
+ifneq (darwin,$(PLATFORM))
+# TODO(bnoordhuis) The native SunOS linker expects -h rather than -soname...
+LDFLAGS_LIB += -Wl,-soname=$(SONAME)
+endif
+
 test: test_g test_fast
 	./test_g
 	./test_fast
@@ -44,7 +74,7 @@ libhttp_parser.o: http_parser.c http_parser.h Makefile
 	$(CC) $(CPPFLAGS_FAST) $(CFLAGS_LIB) -c http_parser.c -o libhttp_parser.o
 
 library: libhttp_parser.o
-	$(CC) -shared -o libhttp_parser.so libhttp_parser.o
+	$(CC) $(LDFLAGS_LIB) -o $(SONAME) $<
 
 package: http_parser.o
 	$(AR) rcs libhttp_parser.a http_parser.o
@@ -66,7 +96,7 @@ tags: http_parser.c http_parser.h test.c
 
 clean:
 	rm -f *.o *.a tags test test_fast test_g \
-		http_parser.tar libhttp_parser.so \
+		http_parser.tar libhttp_parser.so.* \
 		url_parser url_parser_g parsertrace parsertrace_g
 
 contrib/url_parser.c:	http_parser.h
diff --git a/http_parser.h b/http_parser.h
index f7030c4..f624f86 100644
--- a/http_parser.h
+++ b/http_parser.h
@@ -24,6 +24,7 @@
 extern "C" {
 #endif
 
+/* Also update SONAME in the Makefile whenever you change these. */
 #define HTTP_PARSER_VERSION_MAJOR 2
 #define HTTP_PARSER_VERSION_MINOR 1