diff --git a/src/generators/comba_sqr_gen.c b/src/generators/comba_sqr_gen.c
index 57e0737..a949294 100644
--- a/src/generators/comba_sqr_gen.c
+++ b/src/generators/comba_sqr_gen.c
@@ -90,8 +90,9 @@ printf(
 "   B->used = %d;\n"
 "   B->sign = FP_ZPOS;\n"
 "   memcpy(B->dp, b, %d * sizeof(fp_digit));\n"
+"   memset(B->dp + %d, 0, (FP_SIZE - %d) * sizeof(fp_digit));\n"
 "   fp_clamp(B);\n"
-"}\n#endif\n\n\n", N+N, N+N);
+"}\n#endif\n\n\n", N+N, N+N, N+N, N+N);
 
   return 0;
 }
diff --git a/src/generators/comba_sqr_smallgen.c b/src/generators/comba_sqr_smallgen.c
index c6e58c9..d8d62fe 100644
--- a/src/generators/comba_sqr_smallgen.c
+++ b/src/generators/comba_sqr_smallgen.c
@@ -95,8 +95,9 @@ printf(
 "      B->used = %d;\n"
 "      B->sign = FP_ZPOS;\n"
 "      memcpy(B->dp, b, %d * sizeof(fp_digit));\n"
+"      memset(B->dp + %d, 0, (FP_SIZE - %d) * sizeof(fp_digit));\n"
 "      fp_clamp(B);\n"
-"      break;\n\n", N+N, N+N);
+"      break;\n\n", N+N, N+N, N+N, N+N);
 }
 
 printf("}\n\n}\n");