diff --git a/src/modules/image/CompressedData.cpp b/src/modules/image/CompressedData.cpp
index b3aaa6eb7..132e9f784 100644
--- a/src/modules/image/CompressedData.cpp
+++ b/src/modules/image/CompressedData.cpp
@@ -36,18 +36,23 @@ CompressedData::~CompressedData()
 
 int CompressedData::getSize() const
 {
-	size_t totalsize = sizeof(SubImage) * dataImages.size();
-
-	for (size_t i = 0; i < dataImages.size(); i++)
-		totalsize += dataImages[i].size;
-
-	return totalsize;
+	// Adding up the total size for all mipmap levels would make more sense, but
+	// it's probably better for getSize() to match getData() so no bad memory
+	// accesses happen...
+	if (dataImages.size() > 0)
+		return dataImages[0].size;
+	else
+		return 0;
 }
 
 void *CompressedData::getData() const
 {
-	// ?
-	return (void *) &dataImages[0].data[0];
+	// Data for different mipmap levels is not stored contiguously in memory, so
+	// getData() won't work properly for CompressedData.
+	if (dataImages.size() > 0)
+		return (void *) &(dataImages[0].data[0]);
+	else
+		return 0;
 }
 
 int CompressedData::getNumMipmaps() const
diff --git a/src/modules/image/CompressedData.h b/src/modules/image/CompressedData.h
index 9740f30e9..6ffbe6f0c 100644
--- a/src/modules/image/CompressedData.h
+++ b/src/modules/image/CompressedData.h
@@ -70,7 +70,9 @@ public:
 	CompressedData();
 	virtual ~CompressedData();
 
-	// Implements Data.
+	// Implements Data. Note that data for different mipmap levels is not always
+	// stored contiguously in memory, so getData() and getSize() don't make
+	// much sense. Use getData(miplevel) and getSize(mipleveL) instead.
 	virtual void *getData() const;
 	virtual int getSize() const;