diff --git a/src/i3.mk b/src/i3.mk
index 36a24c8b..395b4cfa 100644
--- a/src/i3.mk
+++ b/src/i3.mk
@@ -54,12 +54,12 @@ src/config_parser.o: src/config_parser.c $(i3_HEADERS_DEP) i3-config-parser.stam
 
 i3-command-parser.stamp: generate-command-parser.pl parser-specs/commands.spec
 	echo "[i3] Generating command parser"
-	(cd include; ../generate-command-parser.pl --input=../parser-specs/commands.spec --prefix=command)
+	(cd $(TOPDIR)/include; ../generate-command-parser.pl --input=../parser-specs/commands.spec --prefix=command)
 	touch $@
 
 i3-config-parser.stamp: generate-command-parser.pl parser-specs/config.spec
 	echo "[i3] Generating config parser"
-	(cd include; ../generate-command-parser.pl --input=../parser-specs/config.spec --prefix=config)
+	(cd $(TOPDIR)/include; ../generate-command-parser.pl --input=../parser-specs/config.spec --prefix=config)
 	touch $@
 
 i3: libi3.a $(i3_OBJECTS)
diff --git a/src/log.c b/src/log.c
index 34e34532..86f47b9a 100644
--- a/src/log.c
+++ b/src/log.c
@@ -129,11 +129,16 @@ void open_logbuffer(void) {
             return;
         }
 
+#if defined(__APPLE__)
+        if (ftruncate(logbuffer_shm, logbuffer_size) == -1) {
+            fprintf(stderr, "Could not ftruncate SHM segment for the i3 log: %s\n", strerror(errno));
+#else
         int ret;
         if ((ret = posix_fallocate(logbuffer_shm, 0, logbuffer_size)) != 0) {
+            fprintf(stderr, "Could not ftruncate SHM segment for the i3 log: %s\n", strerror(ret));
+#endif
             close(logbuffer_shm);
             shm_unlink(shmlogname);
-            fprintf(stderr, "Could not ftruncate SHM segment for the i3 log: %s\n", strerror(ret));
             return;
         }