diff --git a/configure.in b/configure.in
index 82e634d..4848e11 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_CONFIG_SRCDIR([lib/lbfgs.c])
 dnl ------------------------------------------------------------------
 dnl Initialization for automake
 dnl ------------------------------------------------------------------
-AM_INIT_AUTOMAKE(liblbfgs, 1.9)
+AM_INIT_AUTOMAKE(liblbfgs, 1.10)
 AC_CONFIG_HEADERS(config.h)
 AM_MAINTAINER_MODE
 
@@ -35,7 +35,7 @@ AC_PROG_MAKE_SET
 dnl ------------------------------------------------------------------
 dnl Initialization for variables
 dnl ------------------------------------------------------------------
-CFLAGS="${ac_save_CFLAGS}"
+CFLAGS="${ac_save_CFLAGS} -Wall"
 LDFLAGS="${ac_save_LDFLAGS}"
 INCLUDES="-I\$(top_srcdir) -I\$(top_srcdir)/include"
 
diff --git a/lib/lbfgs.c b/lib/lbfgs.c
index 0d099ee..30ffcf2 100644
--- a/lib/lbfgs.c
+++ b/lib/lbfgs.c
@@ -656,8 +656,8 @@ static int line_search_backtracking(
     const lbfgs_parameter_t *param
     )
 {
-    int ret = 0, count = 0;
-    lbfgsfloatval_t width, dg, norm = 0.;
+    int count = 0;
+    lbfgsfloatval_t width, dg;
     lbfgsfloatval_t finit, dginit = 0., dgtest;
     const lbfgsfloatval_t dec = 0.5, inc = 2.1;
 
@@ -749,7 +749,7 @@ static int line_search_backtracking_owlqn(
     const lbfgs_parameter_t *param
     )
 {
-    int i, ret = 0, count = 0;
+    int i, count = 0;
     lbfgsfloatval_t width = 0.5, norm = 0.;
     lbfgsfloatval_t finit = *f, dgtest;
 
diff --git a/sample/sample.c b/sample/sample.c
index d36e658..90e36cd 100644
--- a/sample/sample.c
+++ b/sample/sample.c
@@ -44,7 +44,7 @@ static int progress(
 
 #define N   100
 
-int main(int argc, char *argv)
+int main(int argc, char *argv[])
 {
     int i, ret = 0;
     lbfgsfloatval_t fx;