diff --git a/configure.ac b/configure.ac
index b8f4d5a..1801027 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,7 +24,7 @@ you must add '-Iincludedir' to CXXFLAGS
 and '-Llibdir' to LDFLAGS.
 ])])
 pbc_savelibs="$LIBS"
-LIBS="$LIBS -lprotoc -lprotobuf"
+LIBS="$LIBS -lprotoc -lprotobuf -lpthread"
 AC_TRY_LINK([#include <google/protobuf/compiler/command_line_interface.h>],
             [google::protobuf::compiler::CommandLineInterface cli;],
 	    [],
@@ -36,7 +36,7 @@ LIBS="$pbc_savelibs"
 AC_LANG_POP()
 
 dnl Determine the version of the protoc compiler.
-
+dnl (only needed for c++ packed-data comparison)
 if test -n $PROTOC; then
    AC_MSG_CHECKING([which version of protoc is installed])
    raw_vers=`protoc --version 2>/dev/null | sed -e 's/libprotoc //'`
diff --git a/src/Makefile.am b/src/Makefile.am
index 2fde3a7..b728f0e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,7 +19,7 @@ google/protobuf/compiler/c/main.cc \
 google/protobuf/compiler/c/c_bytes_field.cc
 
 protoc_c_LDADD = \
--lprotoc -lprotobuf
+-lprotoc -lprotobuf -lpthread
 
 libprotobuf_c_la_SOURCES = \
 google/protobuf-c/protobuf-c-dispatch.c \