diff --git a/Makefile b/Makefile
index 5188e5d5..3a8cda90 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 PROGS=notmuch
 
-CXXWARNINGS_FLAGS=-Wall
-CWARNINGS_FLAGS=$(CXX_WARNINGS_FLAGS)
+CXXWARNINGS_FLAGS=-Wall -Wextra -Wno-unused-parameter
+CWARNINGS_FLAGS=$(CXXWARNINGS_FLAGS)
 
 CDEPENDS_FLAGS=`pkg-config --cflags glib-2.0 talloc`
 CXXDEPENDS_FLAGS=`pkg-config --cflags glib-2.0 talloc` `xapian-config --cxxflags`
diff --git a/message-file.c b/message-file.c
index cb2bf665..f625a930 100644
--- a/message-file.c
+++ b/message-file.c
@@ -162,7 +162,7 @@ copy_header_unfolding (header_value_closure_t *value,
 	chunk++;
 
     if (value->len + 1 + strlen (chunk) + 1 > value->size) {
-	int new_size = value->size;
+	unsigned int new_size = value->size;
 	if (value->size == 0)
 	    new_size = strlen (chunk) + 1;
 	else
diff --git a/notmuch.c b/notmuch.c
index c5fef0e8..10782d4d 100644
--- a/notmuch.c
+++ b/notmuch.c
@@ -755,7 +755,8 @@ restore_command (int argc, char *argv[])
     FILE *input;
     notmuch_database_t *notmuch = NULL;
     char *line = NULL;
-    size_t line_size, line_len;
+    size_t line_size;
+    ssize_t line_len;
     regex_t regex;
     int rerr;
     int ret = 0;
@@ -893,7 +894,7 @@ void
 usage (void)
 {
     command_t *command;
-    int i;
+    unsigned int i;
 
     fprintf (stderr, "Usage: notmuch <command> [args...]\n");
     fprintf (stderr, "\n");
@@ -911,7 +912,7 @@ int
 main (int argc, char *argv[])
 {
     command_t *command;
-    int i;
+    unsigned int i;
 
     if (argc == 1)
 	return setup_command (0, NULL);
diff --git a/xutil.c b/xutil.c
index 26761d78..6fa5eb0d 100644
--- a/xutil.c
+++ b/xutil.c
@@ -113,7 +113,8 @@ int
 xregexec (const regex_t *preg, const char *string,
 	  size_t nmatch, regmatch_t pmatch[], int eflags)
 {
-    int i, rerr;
+    unsigned int i;
+    int rerr;
 
     rerr = regexec (preg, string, nmatch, pmatch, eflags);
     if (rerr)