diff --git a/src/common/filesystem/resourcefile.h b/src/common/filesystem/resourcefile.h
index 82ba8c7a5e..224f208110 100644
--- a/src/common/filesystem/resourcefile.h
+++ b/src/common/filesystem/resourcefile.h
@@ -3,6 +3,8 @@
 #ifndef __RESFILE_H
 #define __RESFILE_H
 
+#include <limits.h>
+
 #include "files.h"
 
 struct LumpFilterInfo
diff --git a/src/common/utility/cmdlib.cpp b/src/common/utility/cmdlib.cpp
index 2b14df6539..3e108492d0 100644
--- a/src/common/utility/cmdlib.cpp
+++ b/src/common/utility/cmdlib.cpp
@@ -43,6 +43,11 @@
 #include <sys/stat.h>
 #include <time.h>
 
+#ifndef _WIN32
+#include <pwd.h>
+#include <unistd.h>
+#endif
+
 /*
 progdir will hold the path up to the game directory, including the slash
 
diff --git a/src/common/utility/findfile.cpp b/src/common/utility/findfile.cpp
index 9f581c25b3..2c0fd9eace 100644
--- a/src/common/utility/findfile.cpp
+++ b/src/common/utility/findfile.cpp
@@ -40,13 +40,11 @@
 
 #include <fnmatch.h>
 
+#include "cmdlib.h"
+
 static const char *pattern;
 
-#if defined(__APPLE__) && MAC_OS_X_VERSION_MAX_ALLOWED < 1080
-static int matchfile(struct dirent *ent)
-#else
 static int matchfile(const struct dirent *ent)
-#endif
 {
 	return fnmatch(pattern, ent->d_name, FNM_NOESCAPE) == 0;
 }
@@ -187,4 +185,4 @@ const char *I_FindName(findstate_t *fileinfo)
 	return fileinfo->UTF8Name.GetChars();
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/common/utility/findfile.h b/src/common/utility/findfile.h
index 65f121ef58..bcd991e19d 100644
--- a/src/common/utility/findfile.h
+++ b/src/common/utility/findfile.h
@@ -6,6 +6,7 @@
 
 #ifndef _WIN32
 
+#include <dirent.h>
 
 struct findstate_t
 {
diff --git a/src/common/utility/m_alloc.h b/src/common/utility/m_alloc.h
index 3da124bff9..76c4947bce 100644
--- a/src/common/utility/m_alloc.h
+++ b/src/common/utility/m_alloc.h
@@ -38,10 +38,12 @@
 #include <string.h>
 
 #if defined(__APPLE__)
+#include <malloc/malloc.h>
 #define _msize(p)				malloc_size(p)
 #elif defined(__solaris__) || defined(__OpenBSD__)
 #define _msize(p)				(*((size_t*)(p)-1))
 #elif !defined(_WIN32)
+#include <malloc.h>
 #define _msize(p)				malloc_usable_size(p)	// from glibc/FreeBSD
 #endif
 
diff --git a/src/dobject.h b/src/dobject.h
index 071aa3220b..c3e3ae2883 100644
--- a/src/dobject.h
+++ b/src/dobject.h
@@ -37,7 +37,7 @@
 #include <stdlib.h>
 #include <type_traits>
 #include "doomtype.h"
-
+#include "m_alloc.h"
 #include "vectors.h"
 
 class PClass;
diff --git a/src/maploader/usdf.cpp b/src/maploader/usdf.cpp
index 2bca2c3e98..0aae1186c0 100644
--- a/src/maploader/usdf.cpp
+++ b/src/maploader/usdf.cpp
@@ -69,7 +69,7 @@ class USDFParser : public UDMFParserBase
 			PClassActor *cls = PClass::FindActor(CheckString(key));
 			if (cls == nullptr)
 			{
-				sc.ScriptMessage("Unknown actor class '%s'", key);
+				sc.ScriptMessage("Unknown actor class '%s'", key.GetChars());
 				return nullptr;
 			}
 			type = cls;
diff --git a/src/sound/backend/oalsound.cpp b/src/sound/backend/oalsound.cpp
index c6c4af18e8..7590d30d9e 100644
--- a/src/sound/backend/oalsound.cpp
+++ b/src/sound/backend/oalsound.cpp
@@ -2061,6 +2061,7 @@ FSoundChan *OpenALSoundRenderer::FindLowestChannel()
 	return lowest;
 }
 
+#endif // NO_OPENAL
 
 #include "menu/menu.h"
 
@@ -2116,5 +2117,3 @@ void I_BuildALResamplersList(FOptionValues* opt)
 #endif
 }
 
-
-#endif // NO_OPENAL
diff --git a/src/utility/m_random.h b/src/utility/m_random.h
index 71bff03aef..24742efedf 100644
--- a/src/utility/m_random.h
+++ b/src/utility/m_random.h
@@ -37,7 +37,7 @@
 
 #include <stdio.h>
 #include "basics.h"
-#include "SFMT/SFMTObj.h"
+#include "sfmt/SFMTObj.h"
 
 class FSerializer;