diff --git a/includes/media/Bitmap.php b/includes/media/Bitmap.php
index 1be04a7..823f76e 100644
--- a/includes/media/Bitmap.php
+++ b/includes/media/Bitmap.php
@@ -303,27 +303,27 @@ class BitmapHandler extends ImageHandler {
 		global $wgSharpenReductionThreshold, $wgSharpenParameter, $wgMaxAnimatedGifArea,
 			$wgImageMagickTempDir, $wgImageMagickConvertCommand;
 
-		$quality = '';
-		$sharpen = '';
+		$quality = array();
+		$sharpen = array();
 		$scene = false;
-		$animation_pre = '';
-		$animation_post = '';
-		$decoderHint = '';
+		$animation_pre = array();
+		$animation_post = array();
+		$decoderHint = array();
 		if ( $params['mimeType'] == 'image/jpeg' ) {
-			$quality = "-quality 80"; // 80%
+			$quality = array( '-quality', '80' ); // 80%
 			# Sharpening, see bug 6193
 			if ( ( $params['physicalWidth'] + $params['physicalHeight'] )
 				/ ( $params['srcWidth'] + $params['srcHeight'] )
 				< $wgSharpenReductionThreshold
 			) {
-				$sharpen = "-sharpen " . wfEscapeShellArg( $wgSharpenParameter );
+				$sharpen = array( '-sharpen', $wgSharpenParameter );
 			}
 			if ( version_compare( $this->getMagickVersion(), "6.5.6" ) >= 0 ) {
 				// JPEG decoder hint to reduce memory, available since IM 6.5.6-2
-				$decoderHint = "-define jpeg:size={$params['physicalDimensions']}";
+				$decoderHint = array( '-define', "jpeg:size={$params['physicalDimensions']}" );
 			}
 		} elseif ( $params['mimeType'] == 'image/png' ) {
-			$quality = "-quality 95"; // zlib 9, adaptive filtering
+			$quality = array( '-quality', '95' ); // zlib 9, adaptive filtering
 
 		} elseif ( $params['mimeType'] == 'image/gif' ) {
 			if ( $this->getImageArea( $image ) > $wgMaxAnimatedGifArea ) {
@@ -332,15 +332,15 @@ class BitmapHandler extends ImageHandler {
 				$scene = 0;
 			} elseif ( $this->isAnimatedImage( $image ) ) {
 				// Coalesce is needed to scale animated GIFs properly (bug 1017).
-				$animation_pre = '-coalesce';
+				$animation_pre = array( '-coalesce' );
 				// We optimize the output, but -optimize is broken,
 				// use optimizeTransparency instead (bug 11822)
 				if ( version_compare( $this->getMagickVersion(), "6.3.5" ) >= 0 ) {
-					$animation_post = '-fuzz 5% -layers optimizeTransparency';
+					$animation_post = array( '-fuzz', '5%', '-layers', 'optimizeTransparency' );
 				}
 			}
 		} elseif ( $params['mimeType'] == 'image/x-xcf' ) {
-			$animation_post = '-layers merge';
+			$animation_post = array( '-layers', 'merge' );
 		}
 
 		// Use one thread only, to avoid deadlock bugs on OOM
@@ -352,26 +352,28 @@ class BitmapHandler extends ImageHandler {
 		$rotation = $this->getRotation( $image );
 		list( $width, $height ) = $this->extractPreRotationDimensions( $params, $rotation );
 
-		$cmd =
-			wfEscapeShellArg( $wgImageMagickConvertCommand ) .
+		$cmd = call_user_func_array( 'wfEscapeShellArg', array_merge(
+			array( $wgImageMagickConvertCommand ),
+			$quality,
 			// Specify white background color, will be used for transparent images
 			// in Internet Explorer/Windows instead of default black.
-			" {$quality} -background white" .
-			" {$decoderHint} " .
-			wfEscapeShellArg( $this->escapeMagickInput( $params['srcPath'], $scene ) ) .
-			" {$animation_pre}" .
+			array( '-background', 'white' ),
+			$decoderHint,
+			array( $this->escapeMagickInput( $params['srcPath'], $scene ) ),
+			$animation_pre,
 			// For the -thumbnail option a "!" is needed to force exact size,
 			// or ImageMagick may decide your ratio is wrong and slice off
 			// a pixel.
-			" -thumbnail " . wfEscapeShellArg( "{$width}x{$height}!" ) .
+			array( '-thumbnail', "{$width}x{$height}!" ),
 			// Add the source url as a comment to the thumb, but don't add the flag if there's no comment
 			( $params['comment'] !== ''
-				? " -set comment " . wfEscapeShellArg( $this->escapeMagickProperty( $params['comment'] ) )
-				: '' ) .
-			" -depth 8 $sharpen " .
-			" -rotate -$rotation " .
-			" {$animation_post} " .
-			wfEscapeShellArg( $this->escapeMagickOutput( $params['dstPath'] ) );
+				? array( '-set', 'comment', $this->escapeMagickProperty( $params['comment'] ) )
+				: array() ),
+			array( '-depth', 8 ),
+			$sharpen,
+			array( '-rotate', "-$rotation" ),
+			$animation_post,
+			array( $this->escapeMagickOutput( $params['dstPath'] ) ) ) );
 
 		wfDebug( __METHOD__ . ": running ImageMagick: $cmd\n" );
 		wfProfileIn( 'convert' );
@@ -481,8 +483,8 @@ class BitmapHandler extends ImageHandler {
 		$dst = wfEscapeShellArg( $params['dstPath'] );
 		$cmd = $wgCustomConvertCommand;
 		$cmd = str_replace( '%s', $src, str_replace( '%d', $dst, $cmd ) ); # Filenames
-		$cmd = str_replace( '%h', $params['physicalHeight'],
-			str_replace( '%w', $params['physicalWidth'], $cmd ) ); # Size
+		$cmd = str_replace( '%h', wfEscapeShellArg( $params['physicalHeight'] ),
+			str_replace( '%w', wfEscapeShellArg( $params['physicalWidth'] ), $cmd ) ); # Size
 		wfDebug( __METHOD__ . ": Running custom convert command $cmd\n" );
 		wfProfileIn( 'convert' );
 		$retval = 0;
@@ -786,7 +788,7 @@ class BitmapHandler extends ImageHandler {
 			case 'im':
 				$cmd = wfEscapeShellArg( $wgImageMagickConvertCommand ) . " " .
 					wfEscapeShellArg( $this->escapeMagickInput( $params['srcPath'], $scene ) ) .
-					" -rotate -$rotation " .
+					" -rotate " . wfEscapeShellArg( "-$rotation" ) . " " .
 					wfEscapeShellArg( $this->escapeMagickOutput( $params['dstPath'] ) );
 				wfDebug( __METHOD__ . ": running ImageMagick: $cmd\n" );
 				wfProfileIn( 'convert' );