diff --git a/make/makefile b/make/makefile
index 95b9116..8013b41 100644
--- a/make/makefile
+++ b/make/makefile
@@ -92,16 +92,16 @@ install: compiler
 	@$(MKDIR_PARENT) $(DESTDIR)$(bindir)
 	$(INSTALL_PROGRAM) $(project_dir)/bin/oscar64 $(DESTDIR)$(bindir)
 	@$(MKDIR_PARENT) $(DESTDIR)$(includedir)/oscar64/{audio,c64,c128,cx16,gfx,nes,opp,plus4,vic20}
-	$(INSTALL_DATA) $(project_dir)/include/*.h $(DESTDIR)$(includedir)/oscar64
-	$(INSTALL_DATA) $(project_dir)/include/audio/*.h $(DESTDIR)$(includedir)/oscar64/audio
-	$(INSTALL_DATA) $(project_dir)/include/c64/*.h $(DESTDIR)$(includedir)/oscar64/c64
-	$(INSTALL_DATA) $(project_dir)/include/c128/*.h $(DESTDIR)$(includedir)/oscar64/c128
-	$(INSTALL_DATA) $(project_dir)/include/cx16/*.h $(DESTDIR)$(includedir)/oscar64/cx16
-	$(INSTALL_DATA) $(project_dir)/include/gfx/*.h $(DESTDIR)$(includedir)/oscar64/gfx
-	$(INSTALL_DATA) $(project_dir)/include/nes/*.h $(DESTDIR)$(includedir)/oscar64/nes
-	$(INSTALL_DATA) $(project_dir)/include/opp/*.h $(DESTDIR)$(includedir)/oscar64/opp
-	$(INSTALL_DATA) $(project_dir)/include/plus4/*.h $(DESTDIR)$(includedir)/oscar64/plus4
-	$(INSTALL_DATA) $(project_dir)/include/vic20/*.h $(DESTDIR)$(includedir)/oscar64/vic20
+	$(INSTALL_DATA) $(project_dir)/include/*.{h,c} $(DESTDIR)$(includedir)/oscar64
+	$(INSTALL_DATA) $(project_dir)/include/audio/*.{h,c} $(DESTDIR)$(includedir)/oscar64/audio
+	$(INSTALL_DATA) $(project_dir)/include/c64/*.{h,c} $(DESTDIR)$(includedir)/oscar64/c64
+	$(INSTALL_DATA) $(project_dir)/include/c128/*.{h,c} $(DESTDIR)$(includedir)/oscar64/c128
+	$(INSTALL_DATA) $(project_dir)/include/cx16/*.{h,c} $(DESTDIR)$(includedir)/oscar64/cx16
+	$(INSTALL_DATA) $(project_dir)/include/gfx/*.{h,c} $(DESTDIR)$(includedir)/oscar64/gfx
+	$(INSTALL_DATA) $(project_dir)/include/nes/*.{h,c} $(DESTDIR)$(includedir)/oscar64/nes
+	$(INSTALL_DATA) $(project_dir)/include/opp/*.{h,cpp} $(DESTDIR)$(includedir)/oscar64/opp
+	$(INSTALL_DATA) $(project_dir)/include/plus4/*.{h,c} $(DESTDIR)$(includedir)/oscar64/plus4
+	$(INSTALL_DATA) $(project_dir)/include/vic20/*.{h,c} $(DESTDIR)$(includedir)/oscar64/vic20
 
 
 uninstall:
diff --git a/oscar64/oscar64.cpp b/oscar64/oscar64.cpp
index c22d9e7..af9f463 100644
--- a/oscar64/oscar64.cpp
+++ b/oscar64/oscar64.cpp
@@ -113,7 +113,30 @@ int main2(int argc, const char** argv)
 
 		compiler->mPreprocessor->AddPath(basePath);
 		strcpy_s(includePath, basePath);
-		strcat_s(includePath, "include/");
+		{
+			FILE* crtFile;
+			char crtFileNamePath[FILENAME_MAX];
+			crtFileNamePath[FILENAME_MAX - 1] = '\0';
+			strcpy_s(crtFileNamePath, basePath);
+			strcat_s(crtFileNamePath, "include/crt.h");
+
+			if ((crtFile = fopen(crtFileNamePath, "r")))
+				strcat_s(includePath, "include/");
+			else
+			{
+				strcpy_s(crtFileNamePath, basePath);
+				strcat_s(crtFileNamePath, "include/oscar64/crt.h");
+
+				if ((crtFile = fopen(crtFileNamePath, "r")))
+					strcat_s(includePath, "include/oscar64/");
+				else
+				{
+					printf("Could not locate Oscar64 includes under %s\n", basePath);
+					return 20;
+				}
+			}
+			fclose(crtFile);
+		}
 		compiler->mPreprocessor->AddPath(includePath);
 		strcpy_s(crtPath, includePath);
 		strcat_s(crtPath, "crt.c");