diff --git a/config.mk b/config.mk
index 0eb5f27..7056241 100644
--- a/config.mk
+++ b/config.mk
@@ -9,7 +9,7 @@ MANPREFIX = $(PREFIX)/share/man
 
 # flags
 CPPFLAGS = -DVERSION=\"$(VERSION)\" -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=700 -D_BSD_SOURCE
-CFLAGS   = -std=c99 -pedantic -Wno-unused-variable -Wno-implicit-function-declaration -Wall -Os
+CFLAGS   = -std=c99 -pedantic -Wall -Wextra -Os
 LDFLAGS  = -s
 
 # compiler and linker
diff --git a/http.c b/http.c
index 9140cc7..cf08ada 100644
--- a/http.c
+++ b/http.c
@@ -346,7 +346,7 @@ http_send_response(int fd, struct request *r)
 
 		/* if we have a vhost prefix, prepend it to the target */
 		if (s.vhost[i].prefix) {
-			if (snprintf(realtarget, sizeof(realtarget), "%s%s",
+			if ((size_t)snprintf(realtarget, sizeof(realtarget), "%s%s",
 			    s.vhost[i].prefix, realtarget) >= sizeof(realtarget)) {
 				return http_send_status(fd, S_REQUEST_TOO_LARGE);
 			}
@@ -363,8 +363,8 @@ http_send_response(int fd, struct request *r)
 			}
 
 			/* swap out target prefix */
-			if (snprintf(tmptarget, sizeof(tmptarget), "%s%s", s.map[i].to,
-			             realtarget + len) >= sizeof(tmptarget)) {
+			if ((size_t)snprintf(tmptarget, sizeof(tmptarget), "%s%s",
+			    s.map[i].to, realtarget + len) >= sizeof(tmptarget)) {
 				return http_send_status(fd, S_REQUEST_TOO_LARGE);
 			}
 			memcpy(realtarget, tmptarget, sizeof(realtarget));
@@ -441,8 +441,8 @@ http_send_response(int fd, struct request *r)
 
 	if (S_ISDIR(st.st_mode)) {
 		/* append docindex to target */
-		if (snprintf(realtarget, sizeof(realtarget), "%s%s",
-		             r->target, s.docindex) >= sizeof(realtarget)) {
+		if ((size_t)snprintf(realtarget, sizeof(realtarget), "%s%s",
+		    r->target, s.docindex) >= sizeof(realtarget)) {
 			return http_send_status(fd, S_REQUEST_TOO_LARGE);
 		}
 
diff --git a/main.c b/main.c
index 7bcaeed..1c7d285 100644
--- a/main.c
+++ b/main.c
@@ -109,8 +109,9 @@ main(int argc, char *argv[])
 	struct rlimit rlim;
 	struct sockaddr_storage in_sa;
 	pid_t cpid, wpid, spid;
+	size_t i;
 	socklen_t in_sa_len;
-	int i, insock, status = 0, infd;
+	int insock, status = 0, infd;
 	const char *err;
 	char *tok;
 
diff --git a/resp.c b/resp.c
index 7a7d7a2..06714fb 100644
--- a/resp.c
+++ b/resp.c
@@ -75,7 +75,7 @@ resp_dir(int fd, char *name, struct request *r)
 		}
 
 		/* listing */
-		for (i = 0; i < dirlen; i++) {
+		for (i = 0; i < (size_t)dirlen; i++) {
 			/* skip hidden files, "." and ".." */
 			if (e[i]->d_name[0] == '.') {
 				continue;
@@ -165,7 +165,8 @@ resp_file(int fd, char *name, struct request *r, struct stat *st, char *mime,
 		/* write data until upper bound is hit */
 		remaining = upper - lower + 1;
 
-		while ((bread = fread(buf, 1, MIN(sizeof(buf), remaining), fp))) {
+		while ((bread = fread(buf, 1, MIN(sizeof(buf),
+		                      (size_t)remaining), fp))) {
 			if (bread < 0) {
 				return S_INTERNAL_SERVER_ERROR;
 			}