diff --git a/src/shader.cpp b/src/shader.cpp
index 5cfe449..190f3d1 100644
--- a/src/shader.cpp
+++ b/src/shader.cpp
@@ -465,6 +465,17 @@ parseUniformBlocks(memory_arena* arena, shader_program* s, GLContext* gl_ctx)
 	return true;
 }
 
+u32
+getNumAttribComponents(GLenum type)
+{
+	switch (type) {
+		case GL_FLOAT_VEC3: return 3;
+		default:
+			printf("%s(), unknown GLenum\n", __FUNCTION__);
+			return 0;
+	}
+}
+
 bool
 parseAttributes(memory_arena* arena, shader_program* s, GLContext* gl_ctx)
 {
@@ -494,7 +505,8 @@ parseAttributes(memory_arena* arena, shader_program* s, GLContext* gl_ctx)
 		GLVertexAttrib* attrib = &s->vertex_attribs[i];
 		attrib->data_type = type;
 		attrib->location = location;
-		// FIXME: need a helper for attrib->num_components
+		attrib->num_components = getNumAttribComponents(type);
+		assert(attrib->num_components > 0);
 		attrib->name = arenaCopyCStr(arena, attrib_name, sizeof(attrib_name));
 		// TODO: replace POSITION, NORMAL, UV... etc enums in loadGLMesh()
 		// 	with extra logic to detect mesh to shader mapping