diff --git a/Makefile b/Makefile
index 386eca7..b6af27d 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@ LADSPA = $(BOTH)
 VST = $(BOTH) delay_test
 
 UTILS = design bench
-INCLUDES = util util_def param os6iir os2piir
+INCLUDES = util biquad param os6iir os2piir
 
 BENCH_AGAINST = eq_const
 
diff --git a/include/util_def.h b/include/biquad.h
similarity index 87%
rename from include/util_def.h
rename to include/biquad.h
index b0e4047..421d7a9 100644
--- a/include/util_def.h
+++ b/include/biquad.h
@@ -1,32 +1,26 @@
-#include <stdlib.h>
-#include <math.h>
-#include <stdint.h>
-
-INNER void
-disable_denormals()
-{
-	#if __SSE2__
-        _mm_setcsr(_mm_getcsr() | 0x8040);
-	#endif
-}
-
-/* via http://www.rgba.org/articles/sfrand/sfrand.htm */
-static unsigned int mirand = 1;
-
-INNER float
-whitenoise()
-{
-	union either {
-		float f;
-		unsigned int i;
-	} white;
-	mirand *= 16807;
-	white.i = (mirand & 0x007FFFFF) | 0x40000000;
-	return white.f - 3;
-}
-
 /* used to resemble https://github.com/swh/ladspa/blob/master/util/biquad.h */
 
+typedef enum {
+	FILT_PEAKING,
+	FILT_LOWSHELF,
+	FILT_HIGHSHELF,
+	FILT_LOWPASS,
+	FILT_HIGHPASS,
+	FILT_ALLPASS,
+	FILT_BANDPASS,
+	FILT_BANDPASS_2,
+	FILT_NOTCH,
+	FILT_GAIN
+} filter_t;
+
+typedef struct {
+	double a1, a2, b0, b1, b2, x1, x2, y1, y2;
+} biquad;
+
+typedef struct {
+	double b0, b1, b2, a0, a1, a2;
+} biquad_interim;
+
 INNER void
 biquad_init(biquad *bq)
 {
diff --git a/include/util.h b/include/util.h
index 3422c33..0500f0a 100644
--- a/include/util.h
+++ b/include/util.h
@@ -1,4 +1,6 @@
-#include "math.h"
+#include <stdlib.h>
+#include <math.h>
+#include <stdint.h>
 
 #ifdef __SSE2__
 #include <emmintrin.h>
@@ -20,7 +22,15 @@ typedef unsigned long ulong; // __attribute((aligned(16)));
 #define V(x) (v2df){(x), (x)}
 
 INNER void
-disable_denormals();
+disable_denormals()
+{
+	#if __SSE2__
+	_mm_setcsr(_mm_getcsr() | 0x8040);
+	#endif
+}
+
+/* via http://www.rgba.org/articles/sfrand/sfrand.htm */
+static unsigned int mirand = 1;
 
 #define LIMIT(v,l,u) ((v)<(l)?(l):((v)>(u)?(u):(v)))
 #define DB2LIN(x) ((x) > -90 ? pow(10, (x) * 0.05) : 0)
@@ -29,43 +39,16 @@ disable_denormals();
 #define ANGULAR(fc, fs)     (2 * M_PI / (fs) * (fc))
 #define ANGULAR_LIM(fc, fs) (2 * M_PI / (fs) * LIMIT((fc), 1, (fs)/2))
 
-typedef struct {
-	double a1, a2, b0, b1, b2, x1, x2, y1, y2;
-} biquad;
-
-typedef struct {
-	double b0, b1, b2, a0, a1, a2;
-} biquad_interim;
-
 INNER float
-whitenoise();
+whitenoise()
+{
+	union either {
+		float f;
+		unsigned int i;
+	} white;
+	mirand *= 16807;
+	white.i = (mirand & 0x007FFFFF) | 0x40000000;
+	return white.f - 3;
+}
 
-INNER void
-biquad_init(biquad *bq);
-
-typedef enum {
-	FILT_PEAKING,
-	FILT_LOWSHELF,
-	FILT_HIGHSHELF,
-	FILT_LOWPASS,
-	FILT_HIGHPASS,
-	FILT_ALLPASS,
-	FILT_BANDPASS,
-	FILT_BANDPASS_2,
-	FILT_NOTCH,
-	FILT_GAIN
-} filter_t;
-
-INNER biquad
-biquad_gen(filter_t type, double fc, double gain, double bw, double fs);
-
-/* s-plane to z-plane */
-static biquad_interim
-design(double cw, double sw,
-    double num0, double num1, double num2,
-    double den0, double den1, double den2);
-
-INNER double
-biquad_run(biquad *bq, double x);
-
-#include "util_def.h"
+#include "biquad.h"