diff --git a/chain.c b/chain.c
index 9c52e3f..a259499 100644
--- a/chain.c
+++ b/chain.c
@@ -956,7 +956,7 @@
         while (transform != NULL) {
                 // Keep swaping src/dest when performing a transform to use less memory.
                 float *new_src = dest;
-		const void *transform_fn = transform->transform_module_fn;
+		const transform_module_fn_t transform_fn = transform->transform_module_fn;
 		if (transform_fn != qcms_transform_module_gamma_table &&
 		    transform_fn != qcms_transform_module_gamma_lut &&
 		    transform_fn != qcms_transform_module_clut &&
diff --git a/qcmsint.h b/qcmsint.h
index 02ac5ab..0c83053 100644
--- a/qcmsint.h
+++ b/qcmsint.h
@@ -74,6 +74,11 @@
 	float m[3][3];
 	bool invalid;
 };
+
+struct qcms_modular_transform;
+
+typedef void (*transform_module_fn_t)(struct qcms_modular_transform *transform, float *src, float *dest, size_t length);
+
 struct qcms_modular_transform {
 	struct matrix matrix;
 	float tx, ty, tz;
@@ -99,7 +104,7 @@
 	size_t output_gamma_lut_g_length;
 	size_t output_gamma_lut_b_length;
 
-	void (*transform_module_fn)(struct qcms_modular_transform *transform, float *src, float *dest, size_t length);	
+	transform_module_fn_t transform_module_fn;
 	struct qcms_modular_transform *next_transform;
 };