diff --git a/include/libopencm3/stm32/f0/tsc.h b/include/libopencm3/stm32/f0/tsc.h
index fbd65b4b..989451f4 100644
--- a/include/libopencm3/stm32/f0/tsc.h
+++ b/include/libopencm3/stm32/f0/tsc.h
@@ -52,7 +52,7 @@
 #define TSC_IOSCR			MMIO32(TSC_BASE + 0x20)
 #define TSC_IOCCR			MMIO32(TSC_BASE + 0x28)
 #define TSC_IOGCSR			MMIO32(TSC_BASE + 0x30)
-#define TSC_IOGxCR(x)			MMIO8(TSC_BASE + 0x34 + (x)*4)
+#define TSC_IOGxCR(x)			MMIO32(TSC_BASE + 0x34 + ((x)-1)*4)
 
 /*****************************************************************************/
 /* Register values                                                           */