diff --git a/SConstruct b/SConstruct
index d8548f5..ee95a13 100644
--- a/SConstruct
+++ b/SConstruct
@@ -41,7 +41,7 @@ test_lib_includes = ["third-party/unity/src/"]
 VariantDir(variant_dir, ".", duplicate=0)
 # Minimization flags for later:
 # CCFLAGS = ["-Oz", "-flto", "-ffunction-sections", "-fdata-sections", "-Wl,--gc-sections", "-lreadline"]
-CCFLAGS = ["-ggdb", "-O0"]
+CCFLAGS = ["-ggdb", "-O0", "-Werror", "-Wall"]
 env = Environment(
     CPPPATH=lib_includes, COMPILATIONDB_USE_ABSPATH=True, CCFLAGS=CCFLAGS
 )
diff --git a/run_tests.sh.in b/run_tests.sh.in
index 3868185..d3fa494 100755
--- a/run_tests.sh.in
+++ b/run_tests.sh.in
@@ -8,4 +8,4 @@ for test in $TESTS; do
     if [ $? -ne 0 ] ; then
         exit $ret
     fi
-done | tee | grep "Tests"
+done # | tee | grep "Tests"
diff --git a/src/builtins.c b/src/builtins.c
index 6663002..0fa8774 100644
--- a/src/builtins.c
+++ b/src/builtins.c
@@ -31,6 +31,9 @@ LISP_FUNC_1(ucl_builtin_type, scope, arg) {
             assert(0);
             return NULL;
     }
+
+    assert(0);
+    return ucl_error_create("Unreachable error in 'ucl_builtin_type'");
 }
 
 LISP_FUNC_1(ucl_builtin_error, scope, arg) {
@@ -147,7 +150,7 @@ LISP_FUNC_2(ucl_builtin_concat, scope, arg0, arg1) {
     }
 
     int len = strlen(arg0->string) + strlen(arg1->string);
-    char *outstr = malloc(strlen(arg0->string) + strlen(arg1->string));
+    char *outstr = malloc(len);
     outstr[0] = '\0';
     strcat(outstr, arg0->string);
     strcat(outstr, arg1->string);
diff --git a/src/evaluate.c b/src/evaluate.c
index 5c82289..d97376c 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -91,4 +91,7 @@ struct ucl_object *ucl_evaluate(struct ucl_scope *scope, struct ucl_object *obj)
             assert(0);
             return NULL;
     }
+
+    assert(0);
+    return ucl_error_create("Unreachable error in ucl_evaluate");
 }
diff --git a/src/memory.c b/src/memory.c
index 89ca42b..3f3ffd9 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -115,6 +115,7 @@ void ucl_object_delete(struct ucl_object *obj) {
             break;
         case UCL_TYPE_INT:
         case UCL_TYPE_BUILTIN:
+        case UCL_TYPE_SPECIAL:
         case UCL_TYPE_COUNT:
             break;
     }
diff --git a/src/utility.c b/src/utility.c
index 91d5a0d..4265089 100644
--- a/src/utility.c
+++ b/src/utility.c
@@ -144,6 +144,9 @@ void ucl_print_obj(struct ucl_object *obj) {
         case UCL_TYPE_BUILTIN:
             printf("<builtin %p>", obj->builtin);
             break;
+        case UCL_TYPE_SPECIAL:
+            printf("<special %p>", obj->special);
+            break;
         case UCL_TYPE_CELL: {
             int first = true;
             printf("%s", "(");
@@ -212,4 +215,6 @@ struct ucl_object *ucl_equal(
             return ucl_error_create("");
     }
 
+    assert(0);
+    return ucl_error_create("Unreachable error in ucl_equal");
 }
diff --git a/test/test_arena.c b/test/test_arena.c
index a109baf..0975363 100644
--- a/test/test_arena.c
+++ b/test/test_arena.c
@@ -38,7 +38,6 @@ static void test_arena_get_all(void) {
 }
 
 static void test_arena_get_put_limit(void) {
-    struct test_5 *object = NULL;
     struct test_5 *objects[NUM_OBJECTS] = {};
 
     for (int i = 0; i < NUM_OBJECTS; i++) {
@@ -52,7 +51,6 @@ static void test_arena_get_put_limit(void) {
 }
 
 static void test_arena_get_over_limit(void) {
-    struct test_5 *object = NULL;
     struct test_5 *objects[NUM_OBJECTS + 1] = {};
 
     for (int i = 0; i < NUM_OBJECTS + 1; i++) {