diff --git a/src/system/libroot/posix/glibc/stdio-common/printf_fphex.c b/src/system/libroot/posix/glibc/stdio-common/printf_fphex.c
index e38f6510c4..8e977d743e 100644
--- a/src/system/libroot/posix/glibc/stdio-common/printf_fphex.c
+++ b/src/system/libroot/posix/glibc/stdio-common/printf_fphex.c
@@ -138,6 +138,7 @@ do {									      \
 									      \
       /* We use a full nibble for the leading digit.  */		      \
       leading = *numstr++;						      \
+      wnumstr++;							      \
 									      \
       /* We have 3 bits from the mantissa in the leading nibble.	      \
 	 Therefore we are here using `IEEE854_LONG_DOUBLE_BIAS + 3'.  */      \