1 files changed, 3 insertions, 3 deletions

diff --git a/src/nissy.h b/src/nissy.h
index c23f338..a5b3015 100644
--- a/src/nissy.h
+++ b/src/nissy.h
@@ -329,7 +329,7 @@ long long
 nissy_gendata(
         const char *solver,
         unsigned long long data_size,
-        char data[data_size]
+        unsigned char data[data_size]
 );
 
 /*
@@ -347,7 +347,7 @@ Return values:
 long long
 nissy_checkdata(
         unsigned long long data_size,
-        const char data[data_size]
+        const unsigned char data[data_size]
 );
 
 /*
@@ -395,7 +395,7 @@ nissy_solve(
         unsigned optimal,
         unsigned threads,
         unsigned long long data_size,
-        const char data[data_size],
+        const unsigned char data[data_size],
         unsigned sols_size,
         char sols[sols_size],
         long long stats[static NISSY_SIZE_SOLVE_STATS]