diff --git a/arch/arm/include/stm32l4/stm32l4x6xx_irq.h b/arch/arm/include/stm32l4/stm32l4x6xx_irq.h
index 23d5ec42472..b675e786bb8 100644
--- a/arch/arm/include/stm32l4/stm32l4x6xx_irq.h
+++ b/arch/arm/include/stm32l4/stm32l4x6xx_irq.h
@@ -149,8 +149,8 @@
 /* STM32L496xx/4A6xx only: */
 
 #define STM32L4_IRQ_HASH_CRS    (STM32L4_IRQ_FIRST+82) /* 82: HASH and CRS global interrupt */
-#define STM32L4_IRQ_I2C4_EV     (STM32L4_IRQ_FIRST+83) /* 83: I2C4 event interrupt */
-#define STM32L4_IRQ_I2C4_ER     (STM32L4_IRQ_FIRST+84) /* 84: I2C4 error interrupt */
+#define STM32L4_IRQ_I2C4EV      (STM32L4_IRQ_FIRST+83) /* 83: I2C4 event interrupt */
+#define STM32L4_IRQ_I2C4ER      (STM32L4_IRQ_FIRST+84) /* 84: I2C4 error interrupt */
 #define STM32L4_IRQ_DCMI        (STM32L4_IRQ_FIRST+85) /* 85: DCMI global interrupt */
 #define STM32L4_IRQ_CAN2TX      (STM32L4_IRQ_FIRST+86) /* 86: CAN2 TX interrupts */
 #define STM32L4_IRQ_CAN2RX0     (STM32L4_IRQ_FIRST+87) /* 87: CAN2 RX0 interrupts */
diff --git a/arch/arm/src/stm32l4/README.txt b/arch/arm/src/stm32l4/README.txt
index 944be02c29b..9124d966a78 100644
--- a/arch/arm/src/stm32l4/README.txt
+++ b/arch/arm/src/stm32l4/README.txt
@@ -26,7 +26,7 @@ SRAM2    : OK; can be included in MM region or left separate for special app
          : purposes
 FIREWALL : Code written, to be tested, requires support from ldscript
 SPI      : OK, tested (Including DMA)
-I2C      : Code written, to be tested (I2C4 missing)
+I2C      : Code written, to be tested
 RTC      : works
 QSPI     : works in polling, interrupt, DMA, and also memory-mapped modes
 CAN      : OK, tested
@@ -57,7 +57,7 @@ SWP      : TODO (Single wire protocol master, to connect with NFC enabled
 LPUART   : TODO (Low power UART working with LSE at low baud rates)
 LPTIMER  : TODO (Low power TIMER)
 OPAMP    : TODO (Analog operational amplifier)
-COMP     : TODO (Analog comparators)
+COMP     : There is some code (Analog comparators)
 DFSDM    : TODO (Digital Filter and Sigma-Delta Modulator)
 LCD      : TODO (Segment LCD controller)
 SAIPLL   : works (PLL For Digital Audio interfaces, and other things)
diff --git a/arch/arm/src/stm32l4/stm32l4_i2c.c b/arch/arm/src/stm32l4/stm32l4_i2c.c
index 3468af22be2..6df49e444fa 100644
--- a/arch/arm/src/stm32l4/stm32l4_i2c.c
+++ b/arch/arm/src/stm32l4/stm32l4_i2c.c
@@ -96,7 +96,8 @@
 
 /* At least one I2C peripheral must be enabled */
 
-#if defined(CONFIG_STM32L4_I2C1) || defined(CONFIG_STM32L4_I2C2) || defined(CONFIG_STM32L4_I2C3)
+#if defined(CONFIG_STM32L4_I2C1) || defined(CONFIG_STM32L4_I2C2) || \
+    defined(CONFIG_STM32L4_I2C3) || defined(CONFIG_STM32L4_I2C4)
 
 /************************************************************************************
  * Pre-processor Definitions
@@ -300,6 +301,9 @@ static int stm32l4_i2c2_isr(int irq, void *context, FAR void *arg);
 #ifdef CONFIG_STM32L4_I2C3
 static int stm32l4_i2c3_isr(int irq, void *context, FAR void *arg);
 #endif
+#ifdef CONFIG_STM32L4_I2C4
+static int stm32l4_i2c4_isr(int irq, void *context, FAR void *arg);
+#endif
 #endif
 static int stm32l4_i2c_init(FAR struct stm32l4_i2c_priv_s *priv);
 static int stm32l4_i2c_deinit(FAR struct stm32l4_i2c_priv_s *priv);
@@ -413,6 +417,36 @@ struct stm32l4_i2c_priv_s stm32l4_i2c3_priv =
 };
 #endif
 
+#ifdef CONFIG_STM32L4_I2C4
+static const struct stm32l4_i2c_config_s stm32l4_i2c4_config =
+{
+  .base       = STM32L4_I2C4_BASE,
+  .clk_bit    = RCC_APB1ENR2_I2C4EN,
+  .reset_bit  = RCC_APB1RSTR2_I2C4RST,
+  .scl_pin    = GPIO_I2C4_SCL,
+  .sda_pin    = GPIO_I2C4_SDA,
+#ifndef CONFIG_I2C_POLLED
+  .isr        = stm32l4_i2c4_isr,
+  .ev_irq     = STM32L4_IRQ_I2C4EV,
+  .er_irq     = STM32L4_IRQ_I2C4ER
+#endif
+};
+
+struct stm32l4_i2c_priv_s stm32l4_i2c4_priv =
+{
+  .ops        = &stm32l4_i2c_ops,
+  .config     = &stm32l4_i2c4_config,
+  .refs       = 0,
+  .intstate   = INTSTATE_IDLE,
+  .msgc       = 0,
+  .msgv       = NULL,
+  .ptr        = NULL,
+  .dcnt       = 0,
+  .flags      = 0,
+  .status     = 0
+};
+#endif
+
 /************************************************************************************
  * Private Functions
  ************************************************************************************/
@@ -1541,7 +1575,7 @@ static int stm32l4_i2c2_isr(int irq, void *context, FAR void *arg)
  * Name: stm32l4_i2c3_isr
  *
  * Description:
- *   I2C2 interrupt service routine
+ *   I2C3 interrupt service routine
  *
  ************************************************************************************/
 
@@ -1551,7 +1585,22 @@ static int stm32l4_i2c3_isr(int irq, void *context, FAR void *arg)
   return stm32l4_i2c_isr(&stm32l4_i2c3_priv);
 }
 #endif
+
+/************************************************************************************
+ * Name: stm32l4_i2c4_isr
+ *
+ * Description:
+ *   I2C4 interrupt service routine
+ *
+ ************************************************************************************/
+
+#ifdef CONFIG_STM32L4_I2C4
+static int stm32l4_i2c4_isr(int irq, void *context, FAR void *arg)
+{
+  return stm32l4_i2c_isr(&stm32l4_i2c4_priv);
+}
 #endif
+#endif /* !CONFIG_I2C_POLLED */
 
 /************************************************************************************
  * Private Initialization and Deinitialization
@@ -2009,6 +2058,11 @@ FAR struct i2c_master_s *stm32l4_i2cbus_initialize(int port)
       case 3:
         priv = (struct stm32l4_i2c_priv_s *)&stm32l4_i2c3_priv;
         break;
+#endif
+#ifdef CONFIG_STM32L4_I2C4
+      case 4:
+        priv = (struct stm32l4_i2c_priv_s *)&stm32l4_i2c4_priv;
+        break;
 #endif
       default:
         return NULL;
@@ -2072,5 +2126,5 @@ int stm32l4_i2cbus_uninitialize(FAR struct i2c_master_s * dev)
   return OK;
 }
 
-#endif /* CONFIG_STM32L4_I2C1 || CONFIG_STM32L4_I2C2 || CONFIG_STM32L4_I2C3 */
+#endif /* CONFIG_STM32L4_I2C1 || CONFIG_STM32L4_I2C2 || CONFIG_STM32L4_I2C3 || CONFIG_STM32L4_I2C4 */