diff --git a/CMakeLists.txt b/CMakeLists.txt
index a40eadd..23350d5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,21 +10,33 @@ ADD_DEFINITIONS(-D${name}=0)
 ENDIF()
 ENDFUNCTION()
 
-OPTION_AND_DEFINE(XM_DEBUG "Enable debugging messages" "ON")
-OPTION_AND_DEFINE(XM_BIG_ENDIAN "Assume big endian byte order (default: little endian assumed)" "OFF")
+OPTION_AND_DEFINE(XM_DEBUG "Enable debug symbols and print debugging messages to stderr" "ON")
+OPTION_AND_DEFINE(XM_DEFENSIVE "Defensively check XM data for errors/inconsistencies" "ON")
+OPTION_AND_DEFINE(XM_BIG_ENDIAN "Use big endian byte order (unfinished)" "OFF")
 OPTION_AND_DEFINE(XM_LINEAR_INTERPOLATION "Use linear interpolation (CPU hungry)" "ON")
 OPTION_AND_DEFINE(XM_RAMPING "Enable ramping (smooth volume/panning transitions, CPU hungry)" "ON")
 
 OPTION(XM_BUILD_SHARED_LIBS "Build shared library" "ON")
 OPTION(XM_BUILD_EXAMPLES "Build example programs" "ON")
+OPTION(XM_DEMO_MODE "Optimize for size (then link statically against libxms and strip dead code)" "OFF")
 
-ADD_DEFINITIONS("-g -Os -Wall -pedantic --std=c11")
+ADD_DEFINITIONS("-Wall -pedantic --std=c11")
+
+IF(XM_DEBUG)
+ADD_DEFINITIONS("-g")
+ENDIF()
+
+IF(XM_DEMO_MODE)
+ADD_DEFINITIONS("-Os")
 ADD_DEFINITIONS("-fdata-sections -ffunction-sections")
 IF(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
 SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -dead_strip")
 ELSE()
 SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--gc-sections")
 ENDIF()
+ELSE()
+ADD_DEFINITIONS("-O2")
+ENDIF()
 
 LIST(APPEND XM_INCLUDE_DIRS "${libxm_SOURCE_DIR}/include")
 LIST(APPEND XM_LIBRARIES "m")
@@ -34,4 +46,3 @@ ADD_SUBDIRECTORY(src)
 IF(XM_BUILD_EXAMPLES)
 ADD_SUBDIRECTORY(examples)
 ENDIF()
-
diff --git a/Makefile b/Makefile
index 6f2181a..09c0b40 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,11 @@
+build-debug: build
+	@cd build && cmake -D XM_DEBUG=ON -D XM_DEFENSIVE=ON ..
+
+build-demo: build
+	@cd build && cmake -D XM_DEBUG=OFF -D XM_DEFENSIVE=OFF -D XM_DEMO_MODE=ON ..
+
 build:
 	@mkdir -p build
-	@cd build && cmake ..
 
 dist-clean:
 	@rm -Rf build
diff --git a/src/context.c b/src/context.c
index aa0c00b..38aa619 100644
--- a/src/context.c
+++ b/src/context.c
@@ -18,10 +18,12 @@ int xm_create_context_safe(xm_context_t** ctxp, const char* moddata, size_t modd
 	char* mempool;
 	xm_context_t* ctx;
 
-	if((ret = xm_check_header_sanity(moddata, moddata_length))) {
-		DEBUG("xm_check_header_sanity() returned %i", ret);
+#if XM_DEFENSIVE
+	if((ret = xm_check_sanity_preload(moddata, moddata_length))) {
+		DEBUG("xm_check_sanity_preload() returned %i, module is not safe to load", ret);
 		return 1;
 	}
+#endif
 
 	bytes_needed = xm_get_memory_needed_for_context(moddata, moddata_length);
 	mempool = malloc(bytes_needed);
@@ -67,6 +69,14 @@ int xm_create_context_safe(xm_context_t** ctxp, const char* moddata, size_t modd
 	ctx->row_loop_count = (uint8_t*)mempool;
 	mempool += MAX_NUM_ROWS * sizeof(uint8_t);
 
+#if XM_DEFENSIVE
+	if((ret = xm_check_sanity_postload(ctx))) {
+		DEBUG("xm_check_sanity_postload() returned %i, module is not safe to play", ret);
+		xm_free_context(ctx);
+		return 1;
+	}
+#endif
+
 	return 0;
 }
 
diff --git a/src/load.c b/src/load.c
index a5be93e..cc75a43 100644
--- a/src/load.c
+++ b/src/load.c
@@ -33,7 +33,9 @@ static inline void memcpy_pad(void* dst, size_t dst_len, const void* src, size_t
 	memset(dst_c + copy_bytes, 0, dst_len - copy_bytes);
 }
 
-int xm_check_header_sanity(const char* module, size_t module_length) {
+#if XM_DEFENSIVE
+
+int xm_check_sanity_preload(const char* module, size_t module_length) {
 	if(module_length < 60) {
 		return 4;
 	}
@@ -54,6 +56,24 @@ int xm_check_header_sanity(const char* module, size_t module_length) {
 	return 0;
 }
 
+int xm_check_sanity_postload(xm_context_t* ctx) {
+	/* @todo: plenty of stuff to do here… */
+
+	/* Check the POT */
+	for(uint8_t i = 0; i < ctx->module.length; ++i) {
+		if(ctx->module.pattern_table[i] >= ctx->module.num_patterns) {
+			DEBUG("module has invalid POT, pos %i references nonexistent pattern %i",
+			      i,
+			      ctx->module.pattern_table[i]);
+			return 1;
+		}
+	}
+	
+	return 0;
+}
+
+#endif
+
 size_t xm_get_memory_needed_for_context(const char* moddata, size_t moddata_length) {
 	size_t memory_needed = 0;
 	size_t offset = 60; /* Skip the first header */
@@ -153,7 +173,7 @@ char* xm_load_module(xm_context_t* ctx, const char* moddata, size_t moddata_leng
 	mod->patterns = (xm_pattern_t*)mempool;
 	mempool += mod->num_patterns * sizeof(xm_pattern_t);
 
-    mod->instruments = (xm_instrument_t*)mempool;
+	mod->instruments = (xm_instrument_t*)mempool;
 	mempool += mod->num_instruments * sizeof(xm_instrument_t);
 
 	uint16_t flags = READ_U32(offset + 14);
@@ -164,7 +184,7 @@ char* xm_load_module(xm_context_t* ctx, const char* moddata, size_t moddata_leng
 
 	READ_MEMCPY(mod->pattern_table, offset + 20, PATTERN_ORDER_TABLE_LENGTH);
 	offset += header_size;
-
+	
 	/* Read patterns */
 	for(uint16_t i = 0; i < mod->num_patterns; ++i) {
 		uint16_t packed_patterndata_size = READ_U16(offset + 7);
diff --git a/src/xm_internal.h b/src/xm_internal.h
index f019b82..e1aaf43 100644
--- a/src/xm_internal.h
+++ b/src/xm_internal.h
@@ -260,11 +260,21 @@ struct xm_sample_s {
 
 /* ----- Internal API ----- */
 
-/** Check the module header (first 60 bytes).
+#ifdef XM_DEFENSIVE
+
+/** Check the module data for errors/inconsistencies.
+ *
+ * @returns 0 if everything looks OK. Module should be safe to load.
+ */
+int xm_check_sanity_preload(const char*, size_t);
+
+/** Check a loaded module for errors/inconsistencies.
  *
  * @returns 0 if everything looks OK.
  */
-int xm_check_header_sanity(const char*, size_t);
+int xm_check_sanity_postload(xm_context_t*);
+
+#endif
 
 /** Get the number of bytes needed to store the module data in a
  * dynamically allocated blank context.