diff --git a/src/sdl/expr.cpp b/src/sdl/expr.cpp
index f638c67c..cf84caed 100644
--- a/src/sdl/expr.cpp
+++ b/src/sdl/expr.cpp
@@ -103,7 +103,7 @@ using namespace std;
 #include "../elf.h"
 #include "exprNode.h" 
 
-extern int yyerror(char *);
+extern int yyerror(const char *);
 extern int yylex(); 
 extern char *yytext;
 
@@ -1623,7 +1623,7 @@ yyreturn:
 #line 57 "expr.y"
 
 
-int yyerror(char *s)
+int yyerror(const char *s)
 {
   return 0;
 }
diff --git a/src/sdl/expr.y b/src/sdl/expr.y
index 89ef778e..c0be69da 100644
--- a/src/sdl/expr.y
+++ b/src/sdl/expr.y
@@ -12,7 +12,7 @@ using namespace std;
 #include "../elf.h"
 #include "exprNode.h" 
 
-extern int yyerror(char *);
+extern int yyerror(const char *);
 extern int yylex(); 
 extern char *yytext;
 
@@ -56,7 +56,7 @@ ident:
 
 %%
 
-int yyerror(char *s)
+int yyerror(const char *s)
 {
   return 0;
 }
diff --git a/src/sdl/filters.cpp b/src/sdl/filters.cpp
index 17694252..071c21cc 100644
--- a/src/sdl/filters.cpp
+++ b/src/sdl/filters.cpp
@@ -620,7 +620,9 @@ bool sdlStretchInit(int colorDepth, int sizeMultiplier, int srcWidth)
 
 void sdlStretch1x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32 dstPitch, int width, int height) {
     int i;
+#ifndef C_CORE
     u32 *stretcher = (u32 *)sdlStretcher;
+#endif
       for(i = 0; i < height; i++) {
         SDL_CALL_STRETCHER;
         srcPtr += srcPitch;
@@ -629,7 +631,9 @@ void sdlStretch1x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32
 }
 void sdlStretch2x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32 dstPitch, int width, int height) {
     int i;
+#ifndef C_CORE
     u32 *stretcher = (u32 *)sdlStretcher;
+#endif
       for(i = 0; i < height; i++) {
         SDL_CALL_STRETCHER;
         dstPtr += dstPitch;
@@ -640,7 +644,9 @@ void sdlStretch2x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32
 }
 void sdlStretch3x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32 dstPitch, int width, int height) {
     int i;
+#ifndef C_CORE
     u32 *stretcher = (u32 *)sdlStretcher;
+#endif
       for(i = 0; i < height; i++) {
         SDL_CALL_STRETCHER;
         dstPtr += dstPitch;
@@ -653,7 +659,9 @@ void sdlStretch3x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32
 }
 void sdlStretch4x(u8 *srcPtr, u32 srcPitch, u8 * /* deltaPtr */, u8 *dstPtr, u32 dstPitch, int width, int height) {
     int i;
+#ifndef C_CORE
     u32 *stretcher = (u32 *)sdlStretcher;
+#endif
       for(i = 0; i < height; i++) {
         SDL_CALL_STRETCHER;
         dstPtr += dstPitch;