diff --git a/gsk/gl/fp16.c b/gsk/gl/fp16.c
index 0f767e9334..3f67f339ec 100644
--- a/gsk/gl/fp16.c
+++ b/gsk/gl/fp16.c
@@ -45,15 +45,6 @@ half_to_float_one (const guint16 x)
   return as_float((x&0x8000)<<16 | (e!=0)*((e+112)<<23|m) | ((e==0)&(m!=0))*((v-37)<<23|((m<<(150-v))&0x007FE000)));
 }
 
-static inline guint16
-float_to_half_one (const float x)
-{
-  const guint b = as_uint(x)+0x00001000; // round-to-nearest-even
-  const guint e = (b&0x7F800000)>>23; // exponent
-  const guint m = b&0x007FFFFF; // mantissa
-  return (b&0x80000000)>>16 | (e>112)*((((e-112)<<10)&0x7C00)|m>>13) | ((e<113)&(e>101))*((((0x007FF000+m)>>(125-e))+1)>>1) | (e>143)*0x7FFF; // sign : normalized : denormalized : saturate
-}
-
 void
 float_to_half4_c (const float f[4],
                   guint16     h[4])
diff --git a/gsk/gl/fp16private.h b/gsk/gl/fp16private.h
index faeeaa2d81..29e87897d4 100644
--- a/gsk/gl/fp16private.h
+++ b/gsk/gl/fp16private.h
@@ -28,6 +28,26 @@ G_BEGIN_DECLS
 #define FP16_ONE ((guint16)15360)
 #define FP16_MINUS_ONE ((guint16)48128)
 
+static inline guint16
+float_to_half_one (const float x)
+{
+  const guint b = *(guint*)&x+0x00001000; // round-to-nearest-even
+  const guint e = (b&0x7F800000)>>23; // exponent
+  const guint m = b&0x007FFFFF; // mantissa
+  guint n0 = 0;
+  guint n1 = 0;
+  guint n2 = 0;
+
+  if (e > 112)
+    n0 = (((e - 112) << 10) & 0x7C00) | m >> 13;
+  if (e < 113 && e > 101)
+    n1 = (((0x007FF000 + m) >> (125- e)) + 1) >> 1;
+  if (e > 143)
+    n2 = 0x7FFF;
+
+  return (b & 0x80000000) >> 16 | n0 | n1 | n2; // sign : normalized : denormalized : saturate
+}
+
 void float_to_half4 (const float f[4],
                      guint16     h[4]);
 
diff --git a/testsuite/gdk/memorytexture.c b/testsuite/gdk/memorytexture.c
index 4f7a3379a9..989f633d5a 100644
--- a/testsuite/gdk/memorytexture.c
+++ b/testsuite/gdk/memorytexture.c
@@ -2,6 +2,8 @@
 
 #include <epoxy/gl.h>
 
+#include "gsk/gl/fp16private.h"
+
 #define N 10
 
 static GdkGLContext *gl_context = NULL;
@@ -59,7 +61,7 @@ as_float (const guint x)
 // IEEE-754 16-bit floating-point format (without infinity): 1-5-10
 //
 static inline float
-half_to_float (const guint16 x)
+half_to_float_one (const guint16 x)
 {
   const guint e = (x&0x7C00)>>10; // exponent
   const guint m = (x&0x03FF)<<13; // mantissa
@@ -67,26 +69,6 @@ half_to_float (const guint16 x)
   return as_float((x&0x8000)<<16 | (e!=0)*((e+112)<<23|m) | ((e==0)&(m!=0))*((v-37)<<23|((m<<(150-v))&0x007FE000)));
 }
 
-static inline guint16
-float_to_half (const float x)
-{
-  const guint b = *(guint*)&x+0x00001000; // round-to-nearest-even
-  const guint e = (b&0x7F800000)>>23; // exponent
-  const guint m = b&0x007FFFFF; // mantissa
-  guint n0 = 0;
-  guint n1 = 0;
-  guint n2 = 0;
-
-  if (e > 112)
-    n0 = (((e - 112) << 10) & 0x7C00) | m >> 13;
-  if (e < 113 && e > 101)
-    n1 = (((0x007FF000 + m) >> (125- e)) + 1) >> 1;
-  if (e > 143)
-    n2 = 0x7FFF;
-
-  return (b & 0x80000000) >> 16 | n0 | n1 | n2; // sign : normalized : denormalized : saturate
-}
-
 static gsize
 gdk_memory_format_bytes_per_pixel (GdkMemoryFormat format)
 {
@@ -432,7 +414,7 @@ gdk_memory_format_pixel_print (GdkMemoryFormat  format,
     case GDK_MEMORY_R16G16B16_FLOAT:
       {
         const guint16 *data16 = (const guint16 *) data;
-        g_string_append_printf (string, "%f %f %f", half_to_float (data16[0]), half_to_float (data16[1]), half_to_float (data16[2]));
+        g_string_append_printf (string, "%f %f %f", half_to_float_one (data16[0]), half_to_float_one (data16[1]), half_to_float_one (data16[2]));
       }
       break;
 
@@ -440,13 +422,13 @@ gdk_memory_format_pixel_print (GdkMemoryFormat  format,
     case GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED:
       {
         const guint16 *data16 = (const guint16 *) data;
-        g_string_append_printf (string, "%f %f %f %f", half_to_float (data16[0]), half_to_float (data16[1]), half_to_float (data16[2]), half_to_float (data16[3]));
+        g_string_append_printf (string, "%f %f %f %f", half_to_float_one (data16[0]), half_to_float_one (data16[1]), half_to_float_one (data16[2]), half_to_float_one (data16[3]));
       }
       break;
     case GDK_MEMORY_A16_FLOAT:
       {
         const guint16 *data16 = (const guint16 *) data;
-        g_string_append_printf (string, "%f", half_to_float (data16[0]));
+        g_string_append_printf (string, "%f", half_to_float_one (data16[0]));
       }
       break;
 
@@ -537,8 +519,8 @@ gdk_memory_format_pixel_equal (GdkMemoryFormat  format,
         guint i;
         for (i = 0; i < gdk_memory_format_bytes_per_pixel (format) / sizeof (guint16); i++)
           {
-            float f1 = half_to_float (((guint16 *) pixel1)[i]);
-            float f2 = half_to_float (((guint16 *) pixel2)[i]);
+            float f1 = half_to_float_one (((guint16 *) pixel1)[i]);
+            float f2 = half_to_float_one (((guint16 *) pixel2)[i]);
             if (!G_APPROX_VALUE (f1, f2, accurate ? 1./65535 : 1./255))
               return FALSE;
           }
@@ -774,9 +756,9 @@ texture_builder_set_pixel (TextureBuilder  *builder,
     case GDK_MEMORY_R16G16B16_FLOAT:
       {
         guint16 pixels[3] = {
-          float_to_half (color->red * color->alpha),
-          float_to_half (color->green * color->alpha),
-          float_to_half (color->blue * color->alpha)
+          float_to_half_one (color->red * color->alpha),
+          float_to_half_one (color->green * color->alpha),
+          float_to_half_one (color->blue * color->alpha)
         };
         memcpy (data, pixels, 3 * sizeof (guint16));
       }
@@ -784,10 +766,10 @@ texture_builder_set_pixel (TextureBuilder  *builder,
     case GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED:
       {
         guint16 pixels[4] = {
-          float_to_half (color->red * color->alpha),
-          float_to_half (color->green * color->alpha),
-          float_to_half (color->blue * color->alpha),
-          float_to_half (color->alpha)
+          float_to_half_one (color->red * color->alpha),
+          float_to_half_one (color->green * color->alpha),
+          float_to_half_one (color->blue * color->alpha),
+          float_to_half_one (color->alpha)
         };
         memcpy (data, pixels, 4 * sizeof (guint16));
       }
@@ -795,10 +777,10 @@ texture_builder_set_pixel (TextureBuilder  *builder,
     case GDK_MEMORY_R16G16B16A16_FLOAT:
       {
         guint16 pixels[4] = {
-          float_to_half (color->red),
-          float_to_half (color->green),
-          float_to_half (color->blue),
-          float_to_half (color->alpha)
+          float_to_half_one (color->red),
+          float_to_half_one (color->green),
+          float_to_half_one (color->blue),
+          float_to_half_one (color->alpha)
         };
         memcpy (data, pixels, 4 * sizeof (guint16));
       }
@@ -889,7 +871,7 @@ texture_builder_set_pixel (TextureBuilder  *builder,
       break;
     case GDK_MEMORY_A16_FLOAT:
       {
-        guint16 pixel = float_to_half (color->alpha);
+        guint16 pixel = float_to_half_one (color->alpha);
         memcpy (data, &pixel, sizeof (guint16));
       }
       break;
diff --git a/testsuite/gsk/scaling.c b/testsuite/gsk/scaling.c
index e247ee9c94..3ad226050f 100644
--- a/testsuite/gsk/scaling.c
+++ b/testsuite/gsk/scaling.c
@@ -2,6 +2,8 @@
 
 #define N 10
 
+#include "gsk/gl/fp16private.h"
+
 struct {
   const char *name;
   GskRenderer * (*create_func) (void);
@@ -63,7 +65,7 @@ as_float (const guint x)
 // IEEE-754 16-bit floating-point format (without infinity): 1-5-10
 //
 static inline float
-half_to_float (const guint16 x)
+half_to_float_one (const guint16 x)
 {
   const guint e = (x&0x7C00)>>10; // exponent
   const guint m = (x&0x03FF)<<13; // mantissa
@@ -71,15 +73,6 @@ half_to_float (const guint16 x)
   return as_float((x&0x8000)<<16 | (e!=0)*((e+112)<<23|m) | ((e==0)&(m!=0))*((v-37)<<23|((m<<(150-v))&0x007FE000)));
 }
 
-static inline guint16
-float_to_half (const float x)
-{
-  const guint b = *(guint*)&x+0x00001000; // round-to-nearest-even
-  const guint e = (b&0x7F800000)>>23; // exponent
-  const guint m = b&0x007FFFFF; // mantissa
-  return (b&0x80000000)>>16 | (e>112)*((((e-112)<<10)&0x7C00)|m>>13) | ((e<113)&(e>101))*((((0x007FF000+m)>>(125-e))+1)>>1) | (e>143)*0x7FFF; // sign : normalized : denormalized : saturate
-}
-
 static gsize
 gdk_memory_format_bytes_per_pixel (GdkMemoryFormat format)
 {
@@ -350,8 +343,8 @@ gdk_memory_format_pixel_equal (GdkMemoryFormat  format,
         guint i;
         for (i = 0; i < gdk_memory_format_bytes_per_pixel (format) / sizeof (guint16); i++)
           {
-            float f1 = half_to_float (((guint16 *) pixel1)[i]);
-            float f2 = half_to_float (((guint16 *) pixel2)[i]);
+            float f1 = half_to_float_one (((guint16 *) pixel1)[i]);
+            float f2 = half_to_float_one (((guint16 *) pixel2)[i]);
             if (!G_APPROX_VALUE (f1, f2, accurate ? 1./65535 : 1./255))
               return FALSE;
           }
@@ -567,9 +560,9 @@ texture_builder_set_pixel (TextureBuilder  *builder,
     case GDK_MEMORY_R16G16B16_FLOAT:
       {
         guint16 pixels[3] = {
-          float_to_half (color->red * color->alpha),
-          float_to_half (color->green * color->alpha),
-          float_to_half (color->blue * color->alpha)
+          float_to_half_one (color->red * color->alpha),
+          float_to_half_one (color->green * color->alpha),
+          float_to_half_one (color->blue * color->alpha)
         };
         memcpy (data, pixels, 3 * sizeof (guint16));
       }
@@ -577,10 +570,10 @@ texture_builder_set_pixel (TextureBuilder  *builder,
     case GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED:
       {
         guint16 pixels[4] = {
-          float_to_half (color->red * color->alpha),
-          float_to_half (color->green * color->alpha),
-          float_to_half (color->blue * color->alpha),
-          float_to_half (color->alpha)
+          float_to_half_one (color->red * color->alpha),
+          float_to_half_one (color->green * color->alpha),
+          float_to_half_one (color->blue * color->alpha),
+          float_to_half_one (color->alpha)
         };
         memcpy (data, pixels, 4 * sizeof (guint16));
       }
@@ -588,10 +581,10 @@ texture_builder_set_pixel (TextureBuilder  *builder,
     case GDK_MEMORY_R16G16B16A16_FLOAT:
       {
         guint16 pixels[4] = {
-          float_to_half (color->red),
-          float_to_half (color->green),
-          float_to_half (color->blue),
-          float_to_half (color->alpha)
+          float_to_half_one (color->red),
+          float_to_half_one (color->green),
+          float_to_half_one (color->blue),
+          float_to_half_one (color->alpha)
         };
         memcpy (data, pixels, 4 * sizeof (guint16));
       }
@@ -682,7 +675,7 @@ texture_builder_set_pixel (TextureBuilder  *builder,
       break;
     case GDK_MEMORY_A16_FLOAT:
       {
-        guint16 pixel = float_to_half (color->alpha);
+        guint16 pixel = float_to_half_one (color->alpha);
         memcpy (data, &pixel, sizeof (guint16));
       }
       break;