diff --git a/src/shader.cpp b/src/shader.cpp
index 949e81c..1cce201 100644
--- a/src/shader.cpp
+++ b/src/shader.cpp
@@ -259,9 +259,11 @@ initTransforms(MemoryArena* arena,
 	xform_ubo->target = GL_UNIFORM_BUFFER;
 	xform_ubo->data_type = GL_FLOAT;
 	xform_ubo->name = arenaCopyCStr(arena, "matrices");
+	xform_ubo->data_size = sizeof(*xforms);
 
 	glBindBuffer(xform_ubo->target, xform_ubo->id);
-	glBufferData(xform_ubo->target, sizeof(*xforms), xforms, GL_DYNAMIC_DRAW);
+	glBufferData(xform_ubo->target, xform_ubo->data_size, xforms,
+				GL_DYNAMIC_DRAW);
 
 	// NOTE: bindbufferbase
 	xform_ubo->binding_idx = gl_ctx->binding_count++;
@@ -330,13 +332,14 @@ loadGLMesh(const Mesh& m,
 		attrib->buf_type = mappings[i].buf_type;
 		u32 type_size = getGLTypeSize(attrib->data_type);
 		assert(type_size > 0);
+		buf.data_size = m.num_vertices * type_size;
 
 		void* mesh_buf_data = getMeshData(m, mappings[i]);
 		assert(mesh_buf_data);
 		initGLAttribBuffer(&buf, GL_ARRAY_BUFFER, attrib);
 		glBindBuffer(buf.target, buf.id);
 		glBufferData(buf.target,
-			m.num_vertices * type_size,
+			buf.data_size,
 			mesh_buf_data,
 			glm.usage);
 		glVertexAttribPointer(attrib->location, attrib->num_components,
@@ -347,9 +350,10 @@ loadGLMesh(const Mesh& m,
 	glGenBuffers(1, &glm.element_buf->id);
 	glm.element_buf->target = GL_ELEMENT_ARRAY_BUFFER;
 	glm.element_buf->data_type = GL_UNSIGNED_SHORT;
+	glm.element_buf->data_size = m.num_indices * sizeof(u16);
 	glBindBuffer(glm.element_buf->target, glm.element_buf->id);
 	glBufferData(glm.element_buf->target,
-		m.num_indices * sizeof(u16),
+		glm.element_buf->data_size,
 		m.indices,
 		glm.usage);
 
diff --git a/src/shader.h b/src/shader.h
index 62758b0..ed3ff7f 100644
--- a/src/shader.h
+++ b/src/shader.h
@@ -94,6 +94,7 @@ struct GLBuffer
 	GLuint id;
 	GLenum target;
 	GLenum data_type;
+	GLuint data_size; // NOTE: size of buffer in bytes
 	// FIXME: we should initialize both of these to UINT_MAX because '0' is a
 	// 	valid location and index
 	GLuint location; // NOTE: if used as backing for vertex attribute
diff --git a/src/tangerine.cpp b/src/tangerine.cpp
index 5ed870f..e1c1d07 100644
--- a/src/tangerine.cpp
+++ b/src/tangerine.cpp
@@ -355,6 +355,7 @@ initLights(MemoryArena* arena, GLContext* gl_ctx, u32 max_lights)
 
 	lights_ubo->target = GL_UNIFORM_BUFFER;
 	lights_ubo->data_type = GL_BYTE;	// NOTE: mixed types in structure
+	lights_ubo->data_size = lb->buf_size;
 	lights_ubo->name = arenaCopyCStr(arena, "lights");
 	assert((GLint) gl_ctx->binding_count < gl_ctx->max_binding_points);
 	lights_ubo->binding_idx = gl_ctx->binding_count++;