diff --git a/src/filter/cto.h b/src/filter/cto.h
index 3c15d224..daa80534 100644
--- a/src/filter/cto.h
+++ b/src/filter/cto.h
@@ -58,10 +58,18 @@ static int F(Filter *f)
         // must not conflict with the mark.
         // Note that unsigned comparison checks both edges of buffer.
         for (ic = 0; ic < size - 5; ic++)
-            if (COND(b,ic) && get_le32(b+ic+1)+ic+1 >= size)
+        {
+            if (!COND(b,ic))
+                continue;
+            jc = get_le32(b+ic+1)+ic+1;
+            if (jc < size)
             {
-                buf[b[ic+1]] |= 1;
+                if (jc + addvalue >= (1u << 24)) // hi 8 bits won't be cto8
+                    return -1;
             }
+            else
+                buf[b[ic+1]] |= 1;
+        }
 
         if (getcto(f, buf) < 0)
             return -1;
@@ -79,8 +87,7 @@ static int F(Filter *f)
         // try to detect 'real' calls only
         if (jc < size)
         {
-            if ((1u<<24)<=(jc+addvalue))  // hi 8 bits won't be cto8
-                return 1;  // fail - buffer not restored
+            assert(jc + addvalue < (1u << 24)); // hi 8 bits won't be cto8
 #ifdef U
             set_be32(b+ic+1,jc+addvalue+cto);
 #endif
diff --git a/src/filter/ctoj.h b/src/filter/ctoj.h
index 25ac5ad4..1fde538f 100644
--- a/src/filter/ctoj.h
+++ b/src/filter/ctoj.h
@@ -57,10 +57,18 @@ static int F(Filter *f)
         memset(buf,0,256);
 
         for (ic = 0; ic < size - 5; ic++)
-            if (COND(b,ic,lastcall) && get_le32(b+ic+1)+ic+1 >= size)
+        {
+            if (!COND(b,ic,lastcall))
+                continue;
+            jc = get_le32(b+ic+1)+ic+1;
+            if (jc < size)
             {
-                buf[b[ic+1]] |= 1;
+                if (jc + addvalue >= (1u << 24)) // hi 8 bits won't be cto8
+                    return -1;
             }
+            else
+                buf[b[ic+1]] |= 1;
+        }
 
         if (getcto(f, buf) < 0)
             return -1;
@@ -78,8 +86,7 @@ static int F(Filter *f)
         // try to detect 'real' calls only
         if (jc < size)
         {
-            if ((1u<<24)<=(jc+addvalue))  // hi 8 bits won't be cto8
-                return 1;  // fail - buffer not restored
+            assert(jc + addvalue < (1u << 24)); // hi 8 bits won't be cto8
 #ifdef U
             set_be32(b+ic+1,jc+addvalue+cto);
 #endif
diff --git a/src/filter/ctok.h b/src/filter/ctok.h
index 202c4b84..e91d6a29 100644
--- a/src/filter/ctok.h
+++ b/src/filter/ctok.h
@@ -58,10 +58,18 @@ static int F(Filter *f)
         memset(buf,0,256);
 
         for (ic = 0; ic < size - 5; ic++)
-            if (COND(b,ic,lastcall,id) && get_le32(b+ic+1)+ic+1 >= size)
+        {
+            if (!COND(b,ic,lastcall,id))
+                continue;
+            jc = get_le32(b+ic+1)+ic+1;
+            if (jc < size)
             {
-                buf[b[ic+1]] |= 1;
+                if (jc + addvalue >= (1u << 24)) // hi 8 bits won't be cto8
+                    return -1;
             }
+            else
+                buf[b[ic+1]] |= 1;
+        }
 
         if (getcto(f, buf) < 0)
             return -1;
@@ -79,8 +87,7 @@ static int F(Filter *f)
         // try to detect 'real' calls only
         if (jc < size)
         {
-            if ((1u<<24)<=(jc+addvalue))  // hi 8 bits won't be cto8
-                return 1;  // fail - buffer not restored
+            assert(jc + addvalue < (1u << 24)); // hi 8 bits won't be cto8
 #ifdef U
             set_be32(b+ic+1,jc+addvalue+cto);
 #endif
diff --git a/src/filteri.cpp b/src/filteri.cpp
index 3f15cf75..2f50031a 100644
--- a/src/filteri.cpp
+++ b/src/filteri.cpp
@@ -109,7 +109,7 @@ umin(unsigned const a, unsigned const b)
 
 #define COND1(b,x)     (b[x] == 0xe8 || b[x] == 0xe9)
 #define COND2(b,x,lc)  (lc!=(x) && 0xf==b[(x)-1] && 0x80<=b[x] && b[x]<=0x8f)
-#define  COND(b,x,lc,id) (COND1(b,x) || ((9<=(0xf&(id))) && COND2(b,x,lc)))
+#define COND(b,x,lc,id) (COND1(b,x) || ((9<=(0xf&(id))) && COND2(b,x,lc)))
 #define F                       f_ctok32_e8e9_bswap_le
 #define U                       u_ctok32_e8e9_bswap_le
 #include "filter/ctok.h"