diff --git a/Makefile b/Makefile
index e3f37f8..5f7beb3 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,7 @@ CFLAGS := -std=c99 -O3 \
 	  -Wc++-compat \
 	  -Wbad-function-cast \
 	  -Wunused-macros \
+	  -Wwrite-strings \
 	  ${shell pkg-config --cflags ${GTK} ${VTE}} \
 	  ${CFLAGS}
 
diff --git a/termite.c b/termite.c
index b96f47e..27dc122 100644
--- a/termite.c
+++ b/termite.c
@@ -437,13 +437,14 @@ int main(int argc, char **argv) {
     GtkWidget *vte = vte_terminal_new();
 
     char **command_argv;
-    char *default_argv[2] = {NULL, NULL};
+    char fallback[] = "/bin/sh";
+    char *default_argv[2] = {fallback, NULL};
 
     if (argc > 1) {
         command_argv = &argv[1];
     } else {
-        default_argv[0] = vte_get_user_shell();
-        if (!default_argv[0]) default_argv[0] = "/bin/sh";
+        char *shell = vte_get_user_shell();
+        if (shell) default_argv[0] = shell;
         command_argv = default_argv;
     }