diff --git a/src/gd.c b/src/gd.c
index 3375eed..aea8015 100644
--- a/src/gd.c
+++ b/src/gd.c
@@ -499,12 +499,6 @@ BGD_DECLARE(int) gdImageColorClosestAlpha (gdImagePtr im, int r, int g, int b, i
 #define HWB_UNDEFINED -1
 #define SETUP_RGB(s, r, g, b) {s.R = r/255.0; s.G = g/255.0; s.B = b/255.0;}
 
-#define MIN(a,b) ((a)<(b)?(a):(b))
-#define MIN3(a,b,c) ((a)<(b)?(MIN(a,c)):(MIN(b,c)))
-#define MAX(a,b) ((a)<(b)?(b):(a))
-#define MAX3(a,b,c) ((a)<(b)?(MAX(b,c)):(MAX(a,c)))
-
-
 /*
  * Theoretically, hue 0 (pure red) is identical to hue 6 in these transforms. Pure
  * red always maps to 6 in this implementation. Therefore UNDEFINED can be
diff --git a/src/gd_filter.c b/src/gd_filter.c
index 7855190..23bc564 100644
--- a/src/gd_filter.c
+++ b/src/gd_filter.c
@@ -30,8 +30,6 @@
 typedef int (BGD_STDCALL *FuncPtr)(gdImagePtr, int, int);
 
 #define GET_PIXEL_FUNCTION(src)(src->trueColor?gdImageGetTrueColorPixel:gdImageGetPixel)
-#define MIN(a,b) ((a)<(b)?(a):(b))
-#define MAX(a,b) ((a)<(b)?(b):(a))
 
 #ifdef _WIN32
 # define GD_SCATTER_SEED() (unsigned int)(time(0) * GetCurrentProcessId())
diff --git a/src/gd_intern.h b/src/gd_intern.h
index 3bf1fa8..f8f3b5d 100644
--- a/src/gd_intern.h
+++ b/src/gd_intern.h
@@ -1,3 +1,5 @@
+/* Internal header for random common utility functions. */
+
 #ifndef GD_INTERN_H
 #define GD_INTERN_H
 
@@ -29,15 +31,11 @@
 
 #include "gd.h"
 
-#ifndef MIN
 #define MIN(a,b) ((a)<(b)?(a):(b))
-#endif
 #define MIN3(a,b,c) ((a)<(b)?(MIN(a,c)):(MIN(b,c)))
-#ifndef MAX
 #define MAX(a,b) ((a)<(b)?(b):(a))
-#endif
 #define MAX3(a,b,c) ((a)<(b)?(MAX(b,c)):(MAX(a,c)))
-
+#define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
 
 typedef enum {
     HORIZONTAL,
diff --git a/src/gd_interpolation.c b/src/gd_interpolation.c
index eeb9d19..ce27220 100644
--- a/src/gd_interpolation.c
+++ b/src/gd_interpolation.c
@@ -93,9 +93,6 @@ static gdImagePtr gdImageRotateNearestNeighbour(gdImagePtr src,
 static gdImagePtr gdImageRotateGeneric(gdImagePtr src, const float degrees,
                                        const int bgColor);
 
-
-#define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
-
 /* only used here, let do a generic fixed point integers later if required by other
    part of GD */
 typedef long gdFixed;
diff --git a/src/gd_tiff.c b/src/gd_tiff.c
index 4020a6f..15e1056 100644
--- a/src/gd_tiff.c
+++ b/src/gd_tiff.c
@@ -71,10 +71,6 @@
 #define GD_INDEXED 4
 #define GD_RGB 5
 
-#define MIN(a,b) (a < b) ? a : b;
-#define MAX(a,b) (a > b) ? a : b;
-
-
 typedef struct tiff_handle {
 	int size;
 	int pos;
diff --git a/src/gdfx.c b/src/gdfx.c
index 557f51c..dfc8fa7 100644
--- a/src/gdfx.c
+++ b/src/gdfx.c
@@ -4,6 +4,7 @@
 
 #include "gd.h"
 #include "gd_errors.h"
+#include "gd_intern.h"
 #include <math.h>
 
 /* In tests this is sufficient to prevent obvious artifacts */
@@ -12,9 +13,6 @@
 #define PI 3.141592
 #define DEG2RAD(x) ((x)*PI/180.)
 
-#define MAX(x,y) ((x) > (y) ? (x) : (y))
-#define MIN(x,y) ((x) < (y) ? (x) : (y))
-
 #define MAX4(x,y,z,w) \
 	((MAX((x),(y))) > (MAX((z),(w))) ? (MAX((x),(y))) : (MAX((z),(w))))
 #define MIN4(x,y,z,w) \
diff --git a/src/gdtestft.c b/src/gdtestft.c
index f50b174..0663bf3 100644
--- a/src/gdtestft.c
+++ b/src/gdtestft.c
@@ -3,15 +3,13 @@
 #endif
 
 #include "gd.h"
+#include "gd_intern.h"
 #include <string.h>
 #include <stdlib.h>
 
 #define PI 3.141592
 #define DEG2RAD(x) ((x)*PI/180.)
 
-#define MAX(x,y) ((x) > (y) ? (x) : (y))
-#define MIN(x,y) ((x) < (y) ? (x) : (y))
-
 #define MAX4(x,y,z,w) \
 	((MAX((x),(y))) > (MAX((z),(w))) ? (MAX((x),(y))) : (MAX((z),(w))))
 #define MIN4(x,y,z,w) \