diff --git a/.gitmodules b/.gitmodules
index 7bcf405..88d3b91 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "lib/libflint"]
 	path = lib/libflint
 	url = https://git.fputs.com/fputs/libflint
+[submodule "lib/uthash"]
+	path = lib/uthash
+	url = https://github.com/troydhanson/uthash
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e896054..2524e84 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,10 +22,10 @@ add_executable(advent ${SRC} ${SRC2015} ${SRC2016} ${SRC2017} ${SRC2018} ${SRC20
 
 if ((${CMAKE_SYSTEM_NAME} STREQUAL "OpenBSD"))
 	target_link_libraries(advent PRIVATE flint)
-	target_include_directories(advent PRIVATE include lib/libflint/include)
+	target_include_directories(advent PRIVATE include lib/libflint/include lib/uthash/src)
 else()
 	find_package(OpenSSL REQUIRED)
 	target_link_libraries(advent PRIVATE bsd flint ${OPENSSL_LIBRARIES})
-	target_include_directories(advent PRIVATE include lib/libflint/include ${OpenSSL_INCLUDE_DIR})
+	target_include_directories(advent PRIVATE include lib/libflint/include lib/uthash/src ${OpenSSL_INCLUDE_DIR})
 endif()
 
diff --git a/lib/uthash b/lib/uthash
new file mode 160000
index 0000000..bf15263
--- /dev/null
+++ b/lib/uthash
@@ -0,0 +1 @@
+Subproject commit bf15263081be6229be31addd48566df93921cb46
diff --git a/src/2015/02.c b/src/2015/02.c
index 0a85243..bc71948 100644
--- a/src/2015/02.c
+++ b/src/2015/02.c
@@ -3,7 +3,7 @@
 #include <string.h>
 
 #include "lfinput.h"
-#include "math.h"
+#include "lfmath.h"
 
 void advent2015day02(void) {
     size_t sz = 0;
diff --git a/src/2015/07.c b/src/2015/07.c
index 5b4120b..e3cc840 100644
--- a/src/2015/07.c
+++ b/src/2015/07.c
@@ -4,7 +4,17 @@
 #include "lfinput.h"
 
 void advent2015day07(void) {
-    char *input = get_input("input/2015/07");
-    printf("Solution for Day 07 of 2015 is not completed yet\n");
-    free(input);
+    size_t sz = 0;
+    char **input = get_lines("input/2015/07", &sz);
+    for (size_t i = 0; i < sz; ++i) {
+        char *buf = malloc(sizeof(char) * 32);
+        size_t sp_sz = 0;
+        char **sp = split(buf, &sp_sz, " ");
+
+
+
+        del_split(sp);
+    }
+
+    del_lines(input);
 }
diff --git a/src/2021/02.c b/src/2021/02.c
index 08dabbf..117966c 100644
--- a/src/2021/02.c
+++ b/src/2021/02.c
@@ -3,6 +3,10 @@
 #include <string.h>
 #include <limits.h>
 
+#ifdef __linux__
+#include <bsd/stdlib.h>
+#endif
+
 #include "lfinput.h"
 
 static void solution(long p2) {