diff --git a/libc/chmod.cpp b/libc/chmod.cpp
index 01c4e146..c27eadc2 100644
--- a/libc/chmod.cpp
+++ b/libc/chmod.cpp
@@ -29,6 +29,8 @@
 // TODO: Implement this in the kernel.
 extern "C" int chmod(const char* path, mode_t mode)
 {
+	(void) path;
+	(void) mode;
 	errno = ENOSYS;
 	return -1;
 }
diff --git a/libc/dlfcn.cpp b/libc/dlfcn.cpp
index 8d476770..7a94884d 100644
--- a/libc/dlfcn.cpp
+++ b/libc/dlfcn.cpp
@@ -29,6 +29,7 @@ static const char* dlerrormsg = NULL;
 
 extern "C" void* dlopen(const char* filename, int mode)
 {
+	(void) mode;
 	dlerrormsg = "Sortix does not yet support dynamic linking";
 	fprintf(stderr, "%s: loading file: %s\n", dlerrormsg, filename);
 	return NULL;
@@ -36,6 +37,7 @@ extern "C" void* dlopen(const char* filename, int mode)
 
 extern "C" void* dlsym(void* handle, const char* name)
 {
+	(void) handle;
 	dlerrormsg = "Sortix does not yet support dynamic linking";
 	fprintf(stderr, "%s: resolving symbol: %s\n", dlerrormsg, name);
 	return NULL;
@@ -43,12 +45,13 @@ extern "C" void* dlsym(void* handle, const char* name)
 
 extern "C" int dlclose(void* handle)
 {
+	(void) handle;
 	return 0;
 }
 
-extern "C" char* dlerror(void* handle)
+extern "C" char* dlerror()
 {
 	const char* result = dlerrormsg;
 	dlerrormsg = NULL;
-	return (char*) dlerrormsg;
+	return (char*) result;
 }
diff --git a/libc/fchmod.cpp b/libc/fchmod.cpp
index 0ab58ca7..3306b44c 100644
--- a/libc/fchmod.cpp
+++ b/libc/fchmod.cpp
@@ -29,6 +29,8 @@
 // TODO: Implement this in the kernel.
 extern "C" int fchmod(int fd, mode_t mode)
 {
+	(void) fd;
+	(void) mode;
 	errno = ENOSYS;
 	return -1;
 }
diff --git a/libc/fputs.cpp b/libc/fputs.cpp
index 6bd755a6..82e7e249 100644
--- a/libc/fputs.cpp
+++ b/libc/fputs.cpp
@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-	Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
+	Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013.
 
 	This file is part of the Sortix C Library.
 
@@ -28,7 +28,8 @@
 extern "C" int fputs(const char* str, FILE* fp)
 {
 	size_t stringlen = strlen(str);
-	int result = fwrite(str, 1, stringlen, fp);
-	if ( result < stringlen ) { return EOF; }
+	size_t result = fwrite(str, 1, stringlen, fp);
+	if ( result < stringlen )
+		return EOF;
 	return result;
 }
diff --git a/libc/heap.cpp b/libc/heap.cpp
index c47e3a27..37191807 100644
--- a/libc/heap.cpp
+++ b/libc/heap.cpp
@@ -375,6 +375,7 @@ static void InsertChunk(Chunk* chunk)
 	assert(chunk->IsSane());
 }
 
+__attribute__((unused))
 static bool ValidateHeap()
 {
 	bool foundbin[NUMBINS];
@@ -524,7 +525,6 @@ extern "C" void* malloc(size_t size)
 			chunk->size -= left;
 			chunk->GetTrailer()->size = chunk->size;
 
-			size_t leftbinindex = BSR(left);
 			Chunk* leftchunk = chunk->RightNeighbor();
 			leftchunk->size = left;
 			Trailer* lefttrailer = leftchunk->GetTrailer();
diff --git a/libc/include/dlfcn.h b/libc/include/dlfcn.h
index c5bf2fe2..38e84ff3 100644
--- a/libc/include/dlfcn.h
+++ b/libc/include/dlfcn.h
@@ -35,7 +35,7 @@ __BEGIN_DECLS
 #define RTLD_LOCAL 0 /* Bit 8 is not set. */
 
 int dlclose(void* handle);
-char* dlerror(void* handle);
+char* dlerror();
 void* dlopen(const char* filename, int mode);
 void* dlsym(void* handle, const char* name);
 
diff --git a/libc/readparamstring.cpp b/libc/readparamstring.cpp
index 43f4fec6..9706c63f 100644
--- a/libc/readparamstring.cpp
+++ b/libc/readparamstring.cpp
@@ -29,7 +29,6 @@
 
 static char* Substring(const char* src, size_t offset, size_t length)
 {
-	size_t srclen = strlen(src);
 	char* dest = new char[length + 1];
 	if ( !dest ) { return NULL; }
 	memcpy(dest, src + offset, length * sizeof(char));
diff --git a/libc/setjmp.c b/libc/setjmp.c
index ef27aba1..d4bd4179 100644
--- a/libc/setjmp.c
+++ b/libc/setjmp.c
@@ -28,12 +28,15 @@
 
 void longjmp(jmp_buf env, int val)
 {
+	(void) env;
+	(void) val;
 	fprintf(stderr, "setjmp(3) and longjmp(3) are unimplemented, abort!\n");
 	abort();
 }
 
 int setjmp(jmp_buf env)
 {
+	(void) env;
 	return 0;
 }
 
diff --git a/libc/umask.cpp b/libc/umask.cpp
index 3a35d87a..e2d73d07 100644
--- a/libc/umask.cpp
+++ b/libc/umask.cpp
@@ -30,5 +30,6 @@
 // TODO: Implement this in the kernel.
 extern "C" mode_t umask(mode_t mask)
 {
+	(void) mask;
 	return 0;
 }
diff --git a/libc/utime.cpp b/libc/utime.cpp
index d852d62d..effd6f92 100644
--- a/libc/utime.cpp
+++ b/libc/utime.cpp
@@ -28,6 +28,8 @@
 
 extern "C" int utime(const char* filepath, const struct utimbuf* times)
 {
+	(void) filepath;
+	(void) times;
 	// TODO: Sure, I did that! There is no kernel support for this yet.
 	return 0;
 }
diff --git a/libc/vfscanf.cpp b/libc/vfscanf.cpp
index 24253014..cac64b8e 100644
--- a/libc/vfscanf.cpp
+++ b/libc/vfscanf.cpp
@@ -75,25 +75,25 @@ extern "C" int vfscanf(FILE* fp, const char* origformat, va_list ap)
 	union { const char* format; const unsigned char* formatuc; };
 	format = origformat;
 	int matcheditems = 0;
-	size_t fieldwidth;
+	size_t fieldwidth = 0;
 	bool escaped = false;
-	bool discard;
-	bool negint;
-	bool intunsigned;
-	bool leadingzero;
-	bool hasprefix;
-	bool string;
-	size_t intparsed;
-	uintmax_t intvalue;
+	bool discard = false;
+	bool negint = false;
+	bool intunsigned = false;
+	bool leadingzero = false;
+	bool hasprefix = false;
+	bool string = false;
+	size_t intparsed = 0;
+	uintmax_t intvalue = 0;
 	int ic;
-	int base;
+	int base = 0;
 	int cval;
 	const size_t UNDO_MAX = 4;
 	int undodata[UNDO_MAX];
 	size_t undoable = 0;
-	size_t strwritten;
-	char* strdest;
-	enum scantype scantype;
+	size_t strwritten = 0;
+	char* strdest = NULL;
+	enum scantype scantype = TYPE_INT;
 	enum scanmode scanmode = MODE_INIT;
 	while ( true )
 	{