diff --git a/libboard_zynq/src/i2c/mod.rs b/libboard_zynq/src/i2c/mod.rs
index 04168d4..a72bbb8 100644
--- a/libboard_zynq/src/i2c/mod.rs
+++ b/libboard_zynq/src/i2c/mod.rs
@@ -190,7 +190,7 @@ impl I2c {
             self.scl_oe(false);
             self.half_period();
             self.scl_oe(true);
-            while self.scl_i() {}   // ensure SCL is low before start() returns
+            while self.scl_i() {}   // ensure SCL is low before toggling SDA
         }
         self.sda_oe(false);
         self.half_period();
@@ -199,7 +199,7 @@ impl I2c {
         // Read ack/nack
         let ack = !self.sda_i();
         self.scl_oe(true);
-        while self.scl_i() {}   // ensure SCL is low before start() returns
+        while self.scl_i() {}   // ensure SCL is low before toggling SDA
         self.sda_oe(true);
         // postcondition: SCL and SDA low
 
@@ -219,7 +219,7 @@ impl I2c {
             self.half_period();
             if self.sda_i() { data |= 1 << bit }
             self.scl_oe(true);
-            while self.scl_i() {}   // ensure SCL is low before start() returns
+            while self.scl_i() {}   // ensure SCL is low so that slave can toggle SDA
         }
         // Send ack/nack
         self.sda_oe(ack);
@@ -227,7 +227,7 @@ impl I2c {
         self.scl_oe(false);
         self.half_period();
         self.scl_oe(true);
-        while self.scl_i() {}   // ensure SCL is low before start() returns
+        while self.scl_i() {}   // ensure SCL is low before toggling SDA
         self.sda_oe(true);
         // postcondition: SCL and SDA low