diff --git a/src/common/filesystem/ancientzip.h b/src/common/filesystem/ancientzip.h
index 3b1497e02..621505504 100644
--- a/src/common/filesystem/ancientzip.h
+++ b/src/common/filesystem/ancientzip.h
@@ -41,7 +41,7 @@ public:
 	int Explode(unsigned char *out, unsigned int outsize, FileReader &in, unsigned int insize, int flags);
 };
 
-class CExplosionError : CRecoverableError
+class CExplosionError : public CRecoverableError
 {
 public:
 	CExplosionError(const char *message) : CRecoverableError(message) {}
diff --git a/src/common/filesystem/filesystem.cpp b/src/common/filesystem/filesystem.cpp
index 7fd559502..0ea4ac7a6 100644
--- a/src/common/filesystem/filesystem.cpp
+++ b/src/common/filesystem/filesystem.cpp
@@ -837,6 +837,7 @@ void FileSystem::InitHashChains (void)
 {
 	unsigned int i, j;
 
+	NumEntries = FileInfo.Size();
 	Hashes.Resize(8 * NumEntries);
 	// Mark all buckets as empty
 	memset(Hashes.Data(), -1, Hashes.Size() * sizeof(Hashes[0]));
@@ -1522,10 +1523,11 @@ const char *FileSystem::GetResourceFileFullName (int rfnum) const noexcept
 
 bool FileSystem::CreatePathlessCopy(const char *name, int id, int /*flags*/)
 {
-	FString name2, type2, path;
+	FString name2=name, type2, path;
 
 	// The old code said 'filename' and ignored the path, this looked like a bug.
-	auto lump = FindFile(name);
+	FixPathSeperator(name2);
+	auto lump = FindFile(name2);
 	if (lump < 0) return false;		// Does not exist.
 
 	auto oldlump = FileInfo[lump];
diff --git a/src/common/rendering/gl/gl_hwtexture.cpp b/src/common/rendering/gl/gl_hwtexture.cpp
index 70c353082..0043a67b8 100644
--- a/src/common/rendering/gl/gl_hwtexture.cpp
+++ b/src/common/rendering/gl/gl_hwtexture.cpp
@@ -312,6 +312,7 @@ bool FHardwareTexture::BindOrCreate(FTexture *tex, int texunit, int clampmode, i
 		{
 			glTextureBytes = 1;
 			forcenofilter = true;
+			needmipmap = false;
 		}
 		int w = 0, h = 0;
 
diff --git a/src/common/utility/cmdlib.h b/src/common/utility/cmdlib.h
index 9c85aa05f..4c4468c98 100644
--- a/src/common/utility/cmdlib.h
+++ b/src/common/utility/cmdlib.h
@@ -99,5 +99,7 @@ inline void fillshort(void* buff, size_t count, uint16_t clear)
 	}
 }
 
+template<typename T> inline constexpr T Sgn(const T& val) { return (val > 0) - (val < 0); }
+
 
 #endif
diff --git a/src/common/utility/m_fixed.h b/src/common/utility/m_fixed.h
index 99115df6e..30209d635 100644
--- a/src/common/utility/m_fixed.h
+++ b/src/common/utility/m_fixed.h
@@ -7,8 +7,11 @@
 
 
 __forceinline constexpr int32_t MulScale(int32_t a, int32_t b, int32_t shift) { return (int32_t)(((int64_t)a * b) >> shift); }
+__forceinline constexpr double MulScaleF(double a, double b, int32_t shift) { return (a * b) * (1. / (uint32_t(1) << shift)); }
 __forceinline constexpr int32_t DMulScale(int32_t a, int32_t b, int32_t c, int32_t d, int32_t shift) { return (int32_t)(((int64_t)a * b + (int64_t)c * d) >> shift); }
+__forceinline constexpr int32_t TMulScale(int32_t a, int32_t b, int32_t c, int32_t d, int32_t e, int32_t f, int32_t shift) { return (int32_t)(((int64_t)a * b + (int64_t)c * d + (int64_t)e * f) >> shift); }
 __forceinline constexpr int32_t DivScale(int32_t a, int32_t b, int shift) { return (int32_t)(((int64_t)a << shift) / b); }
+__forceinline constexpr int64_t DivScaleL(int64_t a, int64_t b, int shift) { return ((a << shift) / b); }
 
 #include "xs_Float.h"