diff --git a/aegisub/libaegisub/common/charset_conv.cpp b/aegisub/libaegisub/common/charset_conv.cpp
index f5b61c3a0..bd9cc1e57 100644
--- a/aegisub/libaegisub/common/charset_conv.cpp
+++ b/aegisub/libaegisub/common/charset_conv.cpp
@@ -84,7 +84,7 @@ struct iconv_fallbacks {
 
 class Converter : public iconv_fallbacks {
 	bool subst;
-	int bomSize;
+	size_t bomSize;
 	char invalidRep[8];
 	size_t invalidRepSize;
 	static void fallback(
@@ -163,7 +163,7 @@ public:
 			// convert at least one extra character
 			char bom[8];
 			char *dst = bom;
-			size_t dstSize = min(8U, bomSize + *outbytesleft);
+			size_t dstSize = min((size_t)8, bomSize + *outbytesleft);
 			const char *src = *inbuf;
 			size_t srcSize = *inbytesleft;
 			iconv(cd, ICONV_CONST_CAST(&src), &srcSize, &dst, &dstSize);
diff --git a/aegisub/libaegisub/common/vfr.cpp b/aegisub/libaegisub/common/vfr.cpp
index 667154842..9bd7aa4ed 100644
--- a/aegisub/libaegisub/common/vfr.cpp
+++ b/aegisub/libaegisub/common/vfr.cpp
@@ -231,7 +231,7 @@ void Framerate::Save(std::string const& filename, int length) const {
 
 	out << "# timecode format v2\n";
 	std::copy(timecodes.begin(), timecodes.end(), std::ostream_iterator<int>(out, "\n"));
-	for (int written = timecodes.size(); written < length; ++written) {
+	for (int written = (int)timecodes.size(); written < length; ++written) {
 		out << TimeAtFrame(written) << std::endl;
 	}
 }
@@ -268,10 +268,10 @@ int Framerate::FrameAtTime(int ms, Time type) const {
 		return (int)floor((ms - timecodes.front()) * fps / 1000.);
 	}
 	if (ms > timecodes.back()) {
-		return round((ms - timecodes.back()) * fps / 1000.) + timecodes.size() - 1;
+		return round((ms - timecodes.back()) * fps / 1000.) + (int)timecodes.size() - 1;
 	}
 
-	return std::distance(std::lower_bound(timecodes.rbegin(), timecodes.rend(), ms, std::greater<int>()), timecodes.rend()) - 1;
+	return (int)std::distance(std::lower_bound(timecodes.rbegin(), timecodes.rend(), ms, std::greater<int>()), timecodes.rend()) - 1;
 }
 
 int Framerate::TimeAtFrame(int frame, Time type) const {
diff --git a/aegisub/libaegisub/include/libaegisub/line_iterator.h b/aegisub/libaegisub/include/libaegisub/line_iterator.h
index 0761b7bf6..5a8f6570c 100644
--- a/aegisub/libaegisub/include/libaegisub/line_iterator.h
+++ b/aegisub/libaegisub/include/libaegisub/line_iterator.h
@@ -47,7 +47,7 @@ class line_iterator : public std::iterator<std::input_iterator_tag, OutputType>
 	std::tr1::shared_ptr<agi::charset::IconvWrapper> conv;
 	int cr; ///< CR character in the source encoding
 	int lf; ///< LF character in the source encoding
-	int width;  ///< width of LF character in the source encoding
+	size_t width;  ///< width of LF character in the source encoding
 
 	/// @brief Convert a string to the output type
 	/// @param str Line read from the file
@@ -161,11 +161,11 @@ void line_iterator<OutputType>::getline(std::string &str) {
 	for (;;) {
 		chr = 0;
 #ifdef _WIN32
-		int read = stream->rdbuf()->_Sgetn_s(buf, 4, width);
+		std::streamsize read = stream->rdbuf()->_Sgetn_s(buf, 4, width);
 #else
-		int read = stream->rdbuf()->sgetn(buf, width);
+		std::streamsize read = stream->rdbuf()->sgetn(buf, width);
 #endif
-		if (read < width) {
+		if (read < (std::streamsize)width) {
 			for (int i = 0; i < read; i++) {
 				str += buf[i];
 			}