diff --git a/renderdoc/maths/formatpacking.h b/renderdoc/maths/formatpacking.h
index c79913849..56989004f 100644
--- a/renderdoc/maths/formatpacking.h
+++ b/renderdoc/maths/formatpacking.h
@@ -53,16 +53,65 @@ inline uint32_t ConvertToR10G10B10A2(Vec4f data)
 
 inline Vec3f ConvertFromR11G11B10(uint32_t data)
 {
-	uint32_t xMantissa = ((data>> 0) & 0x3f);
-	uint32_t xExponent = ((data>> 6) & 0x1f);
-	uint32_t yMantissa = ((data>>11) & 0x3f);
-	uint32_t yExponent = ((data>>17) & 0x1f);
-	uint32_t zMantissa = ((data>>22) & 0x1f);
-	uint32_t zExponent = ((data>>27) & 0x1f);
+	uint32_t mantissas[3] = {
+		(data>> 0) & 0x3f,
+		(data>>11) & 0x3f,
+		(data>>22) & 0x1f,
+	};
+	int32_t exponents[3] = {
+		(data>> 6) & 0x1f,
+		(data>>17) & 0x1f,
+		(data>>27) & 0x1f,
+	};
 
-	return Vec3f((float(xMantissa)/64.0f)*powf(2.0f, (float)xExponent - 15.0f),
-				 (float(yMantissa)/32.0f)*powf(2.0f, (float)yExponent - 15.0f),
-				 (float(zMantissa)/32.0f)*powf(2.0f, (float)zExponent - 15.0f));
+	Vec3f ret;
+	uint32_t *retu = (uint32_t *)&ret.x;
+
+	// floats have 23 bit mantissa, 8bit exponent
+	// R11G11B10 has 6/6/5 bit mantissas, 5bit exponents
+
+	const int mantissaShift[] = { 23-6, 23-6, 23-5 };
+
+	for(int i=0; i < 3; i++)
+	{
+		if(mantissas[i] == 0 && exponents[i] == 0)
+		{
+			retu[i] = 0;
+		}
+		else
+		{
+			if(exponents[i] == 0x1f)
+			{
+				// infinity or nan
+				retu[i] = 0x7f800000 | mantissas[i] << mantissaShift[i];
+			}
+			else if(exponents[i] != 0)
+			{
+				// shift exponent and mantissa to the right range for 32bit floats
+				retu[i] = (exponents[i] + (127-15)) << 23 | mantissas[i] << mantissaShift[i];
+			}
+			else if(exponents[i] == 0)
+			{
+				// we know xMantissa isn't 0 also, or it would have been caught above
+
+				exponents[i] = 1;
+
+				// shift until hidden bit is set
+				while((mantissas[i] & 0x40) == 0)
+				{
+					mantissas[i] <<= 1;
+					exponents[i]--;
+				}
+
+				// remove the hidden bit
+				mantissas[i] &= ~0x40;
+
+				retu[i] = (exponents[i] + (127-15)) << 23 | mantissas[i] << mantissaShift[i];
+			}
+		}
+	}
+
+	return ret;
 }
 
 /*