diff --git a/Makefile b/Makefile
index c18ce86..9d5744c 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ SRCS = $(sort $(wildcard src/*.c))
 OBJS = $(SRCS:.c=.o)
 LOBJS = src/core.o src/common.o src/libproxychains.o
 
-CCFLAGS  = -Wall -O0 -g -std=c99 -D_GNU_SOURCE -pipe -DTHREAD_SAFE -Werror -Wextra -Wunused -Wuninitialized -Wconversion
+CCFLAGS  = -Wall -O0 -g -std=c99 -D_GNU_SOURCE -pipe -DTHREAD_SAFE -Werror -Wextra -Wunused -Wuninitialized -Wconversion -fno-common
 LDFLAGS = -shared -fPIC -ldl -lpthread
 INC     = 
 PIC     = -fPIC
@@ -68,4 +68,4 @@ $(LDSO_PATHNAME): $(LOBJS)
 $(ALL_TOOLS): $(OBJS)
 	$(CC) src/main.o src/common.o -o $(PXCHAINS)
 
-.PHONY: all clean install install-config
\ No newline at end of file
+.PHONY: all clean install install-config
diff --git a/src/core.c b/src/core.c
index 4f40805..052f429 100644
--- a/src/core.c
+++ b/src/core.c
@@ -34,10 +34,15 @@
 #include <sys/time.h>
 #include <stdarg.h>
 #include <assert.h>
+
 #ifdef THREAD_SAFE
-#include <pthread.h>
 pthread_mutex_t internal_ips_lock;
-#endif
+
+#ifdef __APPLE__
+pthread_mutex_t internal_getsrvbyname_lock;
+#endif /* __APPLE__ */
+
+#endif /* THREAD_SAFE */
 
 #include "core.h"
 #include "common.h"
@@ -255,7 +260,7 @@ static int tunnel_to(int sock, ip_type ip, unsigned short port, proxy_type pt, c
 		if(!dns_len)
 			goto err;
 	}
-	
+
 	PDEBUG("host dns %s\n", dns_name ? dns_name : "<NULL>");
 
 	size_t ulen = strlen(user);
@@ -617,7 +622,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
 
 	switch (ct) {
 		case DYNAMIC_TYPE:
-			alive_count = calc_alive(pd, proxy_count);
+			calc_alive(pd, proxy_count);
 			offset = 0;
 			do {
 				if(!(p1 = select_proxy(FIFOLY, pd, proxy_count, &offset)))
@@ -641,7 +646,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
 			break;
 
 		case STRICT_TYPE:
-			alive_count = calc_alive(pd, proxy_count);
+			calc_alive(pd, proxy_count);
 			offset = 0;
 			if(!(p1 = select_proxy(FIFOLY, pd, proxy_count, &offset))) {
 				PDEBUG("select_proxy failed\n");
@@ -830,19 +835,24 @@ void proxy_getserverbyname(const char * service, struct servent *se_buf,
 
 #ifdef __APPLE__
 	struct servent *se;
+
 #ifdef THREAD_SAFE
 	MUTEX_LOCK(&internal_getsrvbyname_lock);
 #endif
-	if(service)
+	if(service) {
 		se = getservbyname(service, NULL);
-	if (!se)
-		memcpy(se_buf, se, buf_len);
-		*se_result = se_buf;
+
+		if ( se != NULL ) {
+			memcpy(se_buf, se, buf_len);
+			*se_result = se_buf;
+		} else {
+			*se_result = NULL;
+		}
+	}
 #ifdef THREAD_SAFE
 	MUTEX_UNLOCK(&internal_getsrvbyname_lock);
 #endif
-
-#endif
+#endif /* __APPLE__ */
 }
 
 int proxy_getaddrinfo(const char *node, const char *service, const struct addrinfo *hints, struct addrinfo **res) {
diff --git a/src/core.h b/src/core.h
index 8b28e7f..46a162e 100644
--- a/src/core.h
+++ b/src/core.h
@@ -41,11 +41,9 @@ extern internal_ip_lookup_table internal_ips;
 
 #ifdef THREAD_SAFE
 #include <pthread.h>
-pthread_mutex_t internal_ips_lock;
 
-#ifdef __APPLE__
-pthread_mutex_t internal_getsrvbyname_lock;
-#endif
+extern pthread_mutex_t internal_ips_lock;
+extern pthread_mutex_t internal_getsrvbyname_lock;
 
 # define MUTEX_LOCK(x) pthread_mutex_lock(x)
 # define MUTEX_UNLOCK(x) pthread_mutex_unlock(x)
@@ -115,10 +113,10 @@ typedef struct hostent* (*gethostbyname_t)(const char *);
 typedef int (*freeaddrinfo_t)(struct addrinfo *);
 typedef struct hostent *(*gethostbyaddr_t) (const void *, socklen_t, int);
 
-typedef int (*getaddrinfo_t)(const char *, const char *, const struct addrinfo *, 
+typedef int (*getaddrinfo_t)(const char *, const char *, const struct addrinfo *,
 			     struct addrinfo **);
 
-typedef int (*getnameinfo_t) (const struct sockaddr *, socklen_t, char *, 
+typedef int (*getnameinfo_t) (const struct sockaddr *, socklen_t, char *,
 			      socklen_t, char *, socklen_t, int);
 
 
@@ -138,7 +136,7 @@ struct gethostbyname_data {
 
 struct hostent* proxy_gethostbyname(const char *name, struct gethostbyname_data *data);
 
-int proxy_getaddrinfo(const char *node, const char *service, 
+int proxy_getaddrinfo(const char *node, const char *service,
 		      const struct addrinfo *hints, struct addrinfo **res);
 void proxy_freeaddrinfo(struct addrinfo *res);