diff --git a/src/common/frequency.c b/src/common/frequency.c
index 248bb0638..ccb3b707f 100644
--- a/src/common/frequency.c
+++ b/src/common/frequency.c
@@ -6,12 +6,20 @@ bool ffFreqAppendNum(uint32_t mhz, FFstrbuf* result)
         return false;
 
     const FFOptionsDisplay* options = &instance.config.display;
-    const char* space = options->freqSpaceBeforeUnit == FF_SPACE_BEFORE_UNIT_NEVER ? "" : " ";
+    bool spaceBeforeUnit = options->freqSpaceBeforeUnit != FF_SPACE_BEFORE_UNIT_NEVER;
     int8_t ndigits = options->freqNdigits;
 
     if (ndigits >= 0)
-        ffStrbufAppendF(result, "%.*f%sGHz", ndigits, mhz / 1000., space);
+    {
+        ffStrbufAppendDouble(result, mhz / 1000., ndigits);
+        if (spaceBeforeUnit) ffStrbufAppendC(result, ' ');
+        ffStrbufAppendS(result, "GHz");
+    }
     else
-        ffStrbufAppendF(result, "%u%sMHz", (unsigned) mhz, space);
+    {
+        ffStrbufAppendUInt(result, mhz);
+        if (spaceBeforeUnit) ffStrbufAppendC(result, ' ');
+        ffStrbufAppendS(result, "MHz");
+    }
     return true;
 }
diff --git a/src/common/library.c b/src/common/library.c
index 27bac3b82..8a47a1039 100644
--- a/src/common/library.c
+++ b/src/common/library.c
@@ -52,7 +52,7 @@ static void* libraryLoad(const char* path, int maxVersion)
     for(int i = maxVersion; i >= 0; --i)
     {
         uint32_t originalLength = pathbuf.length;
-        ffStrbufAppendF(&pathbuf, "%i", i);
+        ffStrbufAppendSInt(&pathbuf, i);
 
         result = dlopen(pathbuf.chars, FF_DLOPEN_FLAGS);
         if(result != NULL)
diff --git a/src/common/parsing.c b/src/common/parsing.c
index 00de9a8d5..668a28773 100644
--- a/src/common/parsing.c
+++ b/src/common/parsing.c
@@ -50,13 +50,21 @@ int8_t ffVersionCompare(const FFVersion* version1, const FFVersion* version2)
 void ffVersionToPretty(const FFVersion* version, FFstrbuf* pretty)
 {
     if(version->major > 0 || version->minor > 0 || version->patch > 0)
-        ffStrbufAppendF(pretty, "%u", version->major);
+    {
+        ffStrbufAppendUInt(pretty, version->major);
+    }
 
     if(version->minor > 0 || version->patch > 0)
-        ffStrbufAppendF(pretty, ".%u", version->minor);
+    {
+        ffStrbufAppendC(pretty, '.');
+        ffStrbufAppendUInt(pretty, version->minor);
+    }
 
     if(version->patch > 0)
-        ffStrbufAppendF(pretty, ".%u", version->patch);
+    {
+        ffStrbufAppendC(pretty, '.');
+        ffStrbufAppendUInt(pretty, version->patch);
+    }
 }
 
 void ffParseGTK(FFstrbuf* buffer, const FFstrbuf* gtk2, const FFstrbuf* gtk3, const FFstrbuf* gtk4)
diff --git a/src/common/size.c b/src/common/size.c
index f32b02181..eafe46a53 100644
--- a/src/common/size.c
+++ b/src/common/size.c
@@ -14,11 +14,13 @@ static void appendNum(FFstrbuf* result, uint64_t bytes, uint32_t base, const cha
         counter++;
     }
 
-    const char* space = options->sizeSpaceBeforeUnit == FF_SPACE_BEFORE_UNIT_NEVER ? "" : " ";
-    if(counter == 0)
-        ffStrbufAppendF(result, "%" PRIu64 "%s%s", bytes, space, prefixes[0]);
+    if (counter == 0)
+        ffStrbufAppendUInt(result, bytes);
     else
-        ffStrbufAppendF(result, "%.*f%s%s", options->sizeNdigits, size, space, prefixes[counter]);
+        ffStrbufAppendDouble(result, size, (int8_t) options->sizeNdigits);
+    if (options->sizeSpaceBeforeUnit != FF_SPACE_BEFORE_UNIT_NEVER)
+        ffStrbufAppendC(result, ' ');
+    ffStrbufAppendS(result, prefixes[counter]);
 }
 
 void ffSizeAppendNum(uint64_t bytes, FFstrbuf* result)