diff --git a/wrlib/imgformat.h b/wrlib/imgformat.h
index eee0f81f..c7e40243 100644
--- a/wrlib/imgformat.h
+++ b/wrlib/imgformat.h
@@ -48,30 +48,30 @@ typedef enum {
 /*
  * Function for Loading in a specific format
  */
-RImage *RLoadPPM(char *file_name);
+RImage *RLoadPPM(const char *file);
 
-RImage *RLoadXPM(RContext *context, char *file);
+RImage *RLoadXPM(RContext *context, const char *file);
 
 #ifdef USE_TIFF
-RImage *RLoadTIFF(char *file, int index);
+RImage *RLoadTIFF(const char *file, int index);
 #endif
 
 #ifdef USE_PNG
-RImage *RLoadPNG(RContext *context, char *file);
+RImage *RLoadPNG(RContext *context, const char *file);
 #endif
 
 #ifdef USE_JPEG
-RImage *RLoadJPEG(RContext *context, char *file);
+RImage *RLoadJPEG(RContext *context, const char *file);
 #endif
 
 #ifdef USE_GIF
-RImage *RLoadGIF(char *file, int index);
+RImage *RLoadGIF(const char *file, int index);
 #endif
 
 /*
  * Function for Saving in a specific format
  */
-Bool RSaveXPM(RImage * image, char *filename);
+Bool RSaveXPM(RImage *image, const char *file);
 
 
 #endif
diff --git a/wrlib/jpeg.c b/wrlib/jpeg.c
index 28642778..2339f516 100644
--- a/wrlib/jpeg.c
+++ b/wrlib/jpeg.c
@@ -91,7 +91,7 @@ static void my_error_exit(j_common_ptr cinfo)
 	longjmp(myerr->setjmp_buffer, 1);
 }
 
-RImage *RLoadJPEG(RContext * context, char *file_name)
+RImage *RLoadJPEG(RContext * context, const char *file_name)
 {
 	RImage *image = NULL;
 	struct jpeg_decompress_struct cinfo;
diff --git a/wrlib/load.c b/wrlib/load.c
index dc17c268..554e2b48 100644
--- a/wrlib/load.c
+++ b/wrlib/load.c
@@ -68,7 +68,7 @@ static int RImageCacheMaxImage = -1;	/* 0 = any size */
 static RCachedImage *RImageCache;
 
 
-static WRImgFormat identFile(char *path);
+static WRImgFormat identFile(const char *path);
 
 
 char **RSupportedFileFormats(void)
@@ -123,7 +123,7 @@ static void init_cache()
 	}
 }
 
-RImage *RLoadImage(RContext * context, char *file, int index)
+RImage *RLoadImage(RContext * context, const char *file, int index)
 {
 	RImage *image = NULL;
 	int i;
@@ -238,7 +238,7 @@ RImage *RLoadImage(RContext * context, char *file, int index)
 	return image;
 }
 
-char *RGetImageFileFormat(char *file)
+char *RGetImageFileFormat(const char *file)
 {
 	switch (identFile(file)) {
 	case IM_XPM:
@@ -272,7 +272,7 @@ char *RGetImageFileFormat(char *file)
 	}
 }
 
-static WRImgFormat identFile(char *path)
+static WRImgFormat identFile(const char *path)
 {
 	FILE *file;
 	unsigned char buffer[32];
diff --git a/wrlib/nxpm.c b/wrlib/nxpm.c
index 5d9d2707..0574fd94 100644
--- a/wrlib/nxpm.c
+++ b/wrlib/nxpm.c
@@ -551,7 +551,7 @@ static void freecolormap(XPMColor * colormap)
 }
 
 /* save routine is common to internal support and library support */
-Bool RSaveXPM(RImage * image, char *filename)
+Bool RSaveXPM(RImage * image, const char *filename)
 {
 	FILE *file;
 	int x, y;
diff --git a/wrlib/png.c b/wrlib/png.c
index 41736a92..fed178e1 100644
--- a/wrlib/png.c
+++ b/wrlib/png.c
@@ -33,7 +33,7 @@
 #include "wraster.h"
 #include "imgformat.h"
 
-RImage *RLoadPNG(RContext * context, char *file)
+RImage *RLoadPNG(RContext *context, const char *file)
 {
 	char *tmp;
 	RImage *image = NULL;
diff --git a/wrlib/ppm.c b/wrlib/ppm.c
index c3863630..63b7bcf9 100644
--- a/wrlib/ppm.c
+++ b/wrlib/ppm.c
@@ -113,7 +113,7 @@ static RImage *load_pixmap(FILE * file, int w, int h, int max, int raw)
 	return NULL;
 }
 
-RImage *RLoadPPM(char *file_name)
+RImage *RLoadPPM(const char *file_name)
 {
 	FILE *file;
 	RImage *image = NULL;
diff --git a/wrlib/save.c b/wrlib/save.c
index 949af1ae..86a66c6e 100644
--- a/wrlib/save.c
+++ b/wrlib/save.c
@@ -35,7 +35,7 @@
 #include "imgformat.h"
 
 
-Bool RSaveImage(RImage * image, char *filename, char *format)
+Bool RSaveImage(RImage * image, const char *filename, const char *format)
 {
 	if (strcmp(format, "XPM") != 0) {
 		RErrorCode = RERR_BADFORMAT;
diff --git a/wrlib/tiff.c b/wrlib/tiff.c
index 979cb5f2..a54596da 100644
--- a/wrlib/tiff.c
+++ b/wrlib/tiff.c
@@ -34,7 +34,7 @@
 #include "wraster.h"
 #include "imgformat.h"
 
-RImage *RLoadTIFF(char *file, int index)
+RImage *RLoadTIFF(const char *file, int index)
 {
 	RImage *image = NULL;
 	TIFF *tif;
diff --git a/wrlib/wraster.h b/wrlib/wraster.h
index 40f031b8..8a144e2d 100644
--- a/wrlib/wraster.h
+++ b/wrlib/wraster.h
@@ -298,7 +298,7 @@ enum {
 char **RSupportedFileFormats(void);
 
 
-char *RGetImageFileFormat(char *file);
+char *RGetImageFileFormat(const char *file);
 
 /*
  * Xlib contexts
@@ -320,7 +320,7 @@ RImage *RCreateImageFromXImage(RContext *context, XImage *image, XImage *mask);
 RImage *RCreateImageFromDrawable(RContext *context, Drawable drawable,
                                  Pixmap mask);
 
-RImage *RLoadImage(RContext *context, char *file, int index);
+RImage *RLoadImage(RContext *context, const char *file, int index);
 
 RImage* RRetainImage(RImage *image);
 
@@ -331,7 +331,7 @@ RImage *RGetImageFromXPMData(RContext *context, char **xpmData);
 /*
  * RImage storing
  */
-Bool RSaveImage(RImage *image, char *filename, char *format);
+Bool RSaveImage(RImage *image, const char *filename, const char *format);
 
 /*
  * Area manipulation
diff --git a/wrlib/xpm.c b/wrlib/xpm.c
index 04307e3f..12aadc60 100644
--- a/wrlib/xpm.c
+++ b/wrlib/xpm.c
@@ -153,7 +153,7 @@ RImage *RGetImageFromXPMData(RContext * context, char **xpmData)
 	return image;
 }
 
-RImage *RLoadXPM(RContext * context, char *file)
+RImage *RLoadXPM(RContext * context, const char *file)
 {
 	Display *dpy = context->dpy;
 	Colormap cmap = context->cmap;
@@ -164,7 +164,7 @@ RImage *RLoadXPM(RContext * context, char *file)
 	int *p;
 	int i;
 
-	i = XpmReadFileToXpmImage(file, &xpm, (XpmInfo *) NULL);
+	i = XpmReadFileToXpmImage((char *)file, &xpm, (XpmInfo *) NULL);
 	if (i != XpmSuccess) {
 		switch (i) {
 		case XpmOpenFailed: