diff --git a/src/gd.h b/src/gd.h
index 50dfe7f..1a33e98 100644
--- a/src/gd.h
+++ b/src/gd.h
@@ -729,6 +729,7 @@ BGD_DECLARE(void) gdImagePngCtxEx (gdImagePtr im, gdIOCtx * out, int level);
 BGD_DECLARE(void) gdImageWBMP (gdImagePtr image, int fg, FILE * out);
 BGD_DECLARE(void) gdImageWBMPCtx (gdImagePtr image, int fg, gdIOCtx * out);
 
+BGD_DECLARE(void *) gdCalloc (size_t nmemb, size_t size);
 /* Guaranteed to correctly free memory returned by the gdImage*Ptr
    functions */
 BGD_DECLARE(void) gdFree (void *m);
diff --git a/src/gdhelpers.c b/src/gdhelpers.c
index 577e9d5..0e6cf61 100644
--- a/src/gdhelpers.c
+++ b/src/gdhelpers.c
@@ -61,7 +61,7 @@ gd_strtok_r (char *s, char *sep, char **state)
 	return result;
 }
 
-void *
+BGD_DECLARE(void *)
 gdCalloc (size_t nmemb, size_t size)
 {
 	return calloc (nmemb, size);