diff --git a/.gitignore b/.gitignore
index 0aef5cc..45fd162 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 *.out
 vgcore*
+/build/
diff --git a/src/vector.c b/vector.c
similarity index 79%
rename from src/vector.c
rename to vector.c
index aa2e89b..b0a322b 100644
--- a/src/vector.c
+++ b/vector.c
@@ -1,6 +1,11 @@
 #include "vector.h"
 
-static Result vec_warn_error(Result error)
+static void   vec_maybe_destroy_element(Vector const *self,
+                                        size_t const  t_index) NONNULL;
+static Result vec_realloc(Vector *const self) NONNULL;
+static Result vec_warn_error(Result error);
+
+Result vec_warn_error(Result error)
 {
 	PERR("%s", error.result.message);
 	return error;
@@ -54,15 +59,15 @@ void *vec_safe_at(Vector const *const self, size_t const t_index)
 	return (t_index >= vec_length(self)) ? NULL : vec_at(self, t_index);
 }
 
-static void vec_maybe_destroy_element(Vector const *self, size_t const t_index)
+void vec_maybe_destroy_element(Vector const *self, size_t const t_index)
 {
-	void *element = vec_at(self, t_index);
 	if (self->destroy) {
+		void *element = vec_at(self, t_index);
 		self->destroy(element);
 	}
 }
 
-static Result vec_realloc(Vector *const self)
+Result vec_realloc(Vector *const self)
 {
 	self->capacity *= 2;
 	self->elements = realloc(self->elements, sizeof(void *) * vec_capacity(self));
@@ -117,3 +122,23 @@ void vec_delete(Vector *const self)
 	free(self->elements);
 	free(self);
 }
+
+size_t vec_length(Vector const *const self)
+{
+	return self->length;
+}
+
+size_t vec_capacity(Vector const *const self)
+{
+	return self->capacity;
+}
+
+void *vec_at(Vector const *const self, size_t const index)
+{
+	return self->elements[index];
+}
+
+void *vec_last(Vector const *const self)
+{
+	return vec_at(self, vec_length(self) - 1);
+}
diff --git a/src/vector.h b/vector.h
similarity index 76%
rename from src/vector.h
rename to vector.h
index 09d6f30..b6e2983 100644
--- a/src/vector.h
+++ b/vector.h
@@ -20,6 +20,7 @@
 #define GRAY          "\x1b[37m"
 
 #define UNINPLEMENTED    printf("%s:%d: Not yet implemented", __FILE__, __LINE__)
+#define NONNULL          __attribute__((nonnull))
 #define INITIAL_CAPACITY 4
 #define PCOMMON(color, format, ...)                                            \
 	fprintf(stderr,                                                              \
@@ -53,30 +54,14 @@ typedef struct Result_s {
 
 Result vec_new(Destructor destructor);
 Result vec_with_capacity(Destructor const destructor, size_t const capacity);
-Result vec_push(Vector *const self, void *const element);
-Result vec_shrink_to_fit(Vector *const self);
-void * vec_safe_at(Vector const *const self, size_t const index);
-void   vec_pop(Vector *const self);
-void   vec_delete(Vector *const self);
-
-inline size_t vec_length(Vector const *const self)
-{
-	return self->length;
-}
-
-inline size_t vec_capacity(Vector const *const self)
-{
-	return self->capacity;
-}
-
-inline void *vec_at(Vector const *const self, size_t const index)
-{
-	return self->elements[index];
-}
-
-inline void *vec_last(Vector const *const self)
-{
-	return vec_at(self, vec_length(self) - 1);
-}
+Result vec_push(Vector *const self, void *const element) NONNULL;
+Result vec_shrink_to_fit(Vector *const self) NONNULL;
+void * vec_safe_at(Vector const *const self, size_t const index) NONNULL;
+void * vec_at(Vector const *const self, size_t const index) NONNULL;
+void * vec_last(Vector const *const self) NONNULL;
+void   vec_pop(Vector *const self) NONNULL;
+void   vec_delete(Vector *const self) NONNULL;
+size_t vec_length(Vector const *const self) NONNULL;
+size_t vec_capacity(Vector const *const self) NONNULL;
 
 #endif /* VECTOR_H */