diff --git a/tjbench.c b/tjbench.c
index f135da46..ebad24ea 100644
--- a/tjbench.c
+++ b/tjbench.c
@@ -217,7 +217,7 @@ int decomptest(unsigned char *srcbuf, unsigned char **jpegbuf,
 						dstbuf[bindex]=abs(dstbuf[bindex]-y);
 					}
 				}
-			}		
+			}
 			else
 			{
 				for(row=0; row<h; row++)
@@ -239,7 +239,7 @@ int decomptest(unsigned char *srcbuf, unsigned char **jpegbuf,
 }
 
 
-void dotestyuv(unsigned char *srcbuf, int w, int h, int subsamp,
+int dotestyuv(unsigned char *srcbuf, int w, int h, int subsamp,
 	char *filename)
 {
 	char tempstr[1024], tempstr2[80];
@@ -311,11 +311,11 @@ void dotestyuv(unsigned char *srcbuf, int w, int h, int subsamp,
 	if(file) {fclose(file);  file=NULL;}
 	if(dstbuf) {free(dstbuf);  dstbuf=NULL;}
 	if(handle) {tjDestroy(handle);  handle=NULL;}
-	return;
+	return retval;
 }
 
 
-void dotest(unsigned char *srcbuf, int w, int h, int subsamp, int jpegqual,
+int dotest(unsigned char *srcbuf, int w, int h, int subsamp, int jpegqual,
 	char *filename)
 {
 	char tempstr[1024], tempstr2[80];
@@ -326,7 +326,7 @@ void dotest(unsigned char *srcbuf, int w, int h, int subsamp, int jpegqual,
 	unsigned long *jpegsize=NULL;
 	int ps=tjPixelSize[pf], ntilesw=1, ntilesh=1, pitch=w*ps;
 
-	if(yuv==YUVENCODE) {dotestyuv(srcbuf, w, h, subsamp, filename);  return;}
+	if(yuv==YUVENCODE) return dotestyuv(srcbuf, w, h, subsamp, filename);
 
 	if((tmpbuf=(unsigned char *)malloc(pitch*h)) == NULL)
 		_throwunix("allocating temporary image buffer");
@@ -457,11 +457,11 @@ void dotest(unsigned char *srcbuf, int w, int h, int subsamp, int jpegqual,
 	if(jpegsize) {free(jpegsize);  jpegsize=NULL;}
 	if(tmpbuf) {free(tmpbuf);  tmpbuf=NULL;}
 	if(handle) {tjDestroy(handle);  handle=NULL;}
-	return;
+	return retval;
 }
 
 
-void dodecomptest(char *filename)
+int dodecomptest(char *filename)
 {
 	FILE *file=NULL;  tjhandle handle=NULL;
 	unsigned char **jpegbuf=NULL, *srcbuf=NULL;
@@ -660,7 +660,7 @@ void dodecomptest(char *filename)
 	if(srcbuf) {free(srcbuf);  srcbuf=NULL;}
 	if(t) {free(t);  t=NULL;}
 	if(handle) {tjDestroy(handle);  handle=NULL;}
-	return;
+	return retval;
 }
 
 
diff --git a/turbojpeg.c b/turbojpeg.c
index 9117273d..7b9811d5 100644
--- a/turbojpeg.c
+++ b/turbojpeg.c
@@ -120,6 +120,16 @@ static const tjscalingfactor sf[NUMSF]={
 	if(!this) {snprintf(errStr, JMSG_LENGTH_MAX, "Invalid handle");  \
 		return -1;}  \
 	cinfo=&this->cinfo;  dinfo=&this->dinfo;
+#define getcinstance(handle) tjinstance *this=(tjinstance *)handle;  \
+	j_compress_ptr cinfo=NULL;  \
+	if(!this) {snprintf(errStr, JMSG_LENGTH_MAX, "Invalid handle");  \
+		return -1;}  \
+	cinfo=&this->cinfo;
+#define getdinstance(handle) tjinstance *this=(tjinstance *)handle;  \
+	j_decompress_ptr dinfo=NULL;  \
+	if(!this) {snprintf(errStr, JMSG_LENGTH_MAX, "Invalid handle");  \
+		return -1;}  \
+	dinfo=&this->dinfo;
 
 static int getPixelFormat(int pixelSize, int flags)
 {
@@ -580,7 +590,7 @@ DLLEXPORT int DLLCALL tjCompress2(tjhandle handle, unsigned char *srcBuf,
 	unsigned char *rgbBuf=NULL;
 	#endif
 
-	getinstance(handle)
+	getcinstance(handle)
 	if((this->init&COMPRESS)==0)
 		_throw("tjCompress2(): Instance has not been initialized for compression");
 
@@ -685,7 +695,7 @@ DLLEXPORT int DLLCALL tjEncodeYUV2(tjhandle handle, unsigned char *srcBuf,
 	unsigned char *rgbBuf=NULL;
 	#endif
 
-	getinstance(handle);
+	getcinstance(handle);
 
 	for(i=0; i<MAX_COMPONENTS; i++)
 	{
@@ -881,7 +891,7 @@ DLLEXPORT int DLLCALL tjDecompressHeader2(tjhandle handle,
 {
 	int retval=0;
 
-	getinstance(handle);
+	getdinstance(handle);
 	if((this->init&DECOMPRESS)==0)
 		_throw("tjDecompressHeader2(): Instance has not been initialized for decompression");
 
@@ -947,7 +957,7 @@ DLLEXPORT int DLLCALL tjDecompress2(tjhandle handle, unsigned char *jpegBuf,
 	unsigned char *_dstBuf=NULL;  int _pitch=0;
 	#endif
 
-	getinstance(handle);
+	getdinstance(handle);
 	if((this->init&DECOMPRESS)==0)
 		_throw("tjDecompress2(): Instance has not been initialized for decompression");
 
@@ -1058,7 +1068,7 @@ DLLEXPORT int DLLCALL tjDecompressToYUV(tjhandle handle,
 		tmpbufsize=0, usetmpbuf=0, th[MAX_COMPONENTS];
 	JSAMPLE *_tmpbuf=NULL, *ptr=dstBuf;  JSAMPROW *tmpbuf[MAX_COMPONENTS];
 
-	getinstance(handle);
+	getdinstance(handle);
 
 	for(i=0; i<MAX_COMPONENTS; i++)
 	{